9QK2 | pdb_00009qk2

Structure of the Complement classical and lectin pathway C3 convertase in complex with substrate C3

External Resource: Annotation

Domain Annotation: SCOP2 Classification
SAbDab Antibody Annotation
Protein Family Annotation
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification
Pharos: Disease Associations

Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

Chains	Type	Family Name	Domain Identifier	Family Identifier	Provenance Source (Version)
G	SCOP2B Superfamily	Terpenoid cyclases/Protein prenyltransferases	8038414	3001024	SCOP2B (2022-06-29)
D [auth B]	SCOP2B Superfamily	Terpenoid cyclases/Protein prenyltransferases	8042441	3001024	SCOP2B (2022-06-29)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
E [auth D]	Heavy Chain	IGHV1	-	complement c4-a \| complement c4-a	SAbDab (2026-01-23)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
F, G	PF17790	Macroglobulin domain MG1 (MG1)	Macroglobulin domain MG1	This entry represents the N-terminal macroglobulin domain found in complement proteins C3, C4 and C5.	Domain
F, G	PF01821	Anaphylotoxin-like domain (ANATO)	Anaphylotoxin-like domain	C3a, C4a and C5a anaphylatoxins are protein fragments generated enzymatically in serum during activation of complement molecules C3, C4, and C5. They induce smooth muscle contraction. These fragments are homologous to a three-fold repeat in fibulins. ...	C3a, C4a and C5a anaphylatoxins are protein fragments generated enzymatically in serum during activation of complement molecules C3, C4, and C5. They induce smooth muscle contraction. These fragments are homologous to a three-fold repeat in fibulins.	Domain
F, G	PF17791	Macroglobulin domain MG3 (MG3)	Macroglobulin domain MG3	This entry corresponds to the MG3 domain found in complement components C3, C4 and C5.	Domain
F, G	PF01835	MG2 domain (MG2)	MG2 domain	This is the MG2 (macroglobulin) domain of alpha-2-macroglobulin in eukaryotes [1]. Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. How ...	This is the MG2 (macroglobulin) domain of alpha-2-macroglobulin in eukaryotes [1]. Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and species that colonize higher eukaryotes. This domain is found in eukaryotic and bacterial proteins. In human A2Ms, this domain is termed macroglobulin-like (MG) domain 2 and in Salmonella enterica ser A2Ms, this is domain 4 [2] [3].	Domain
F, G	PF00207	Alpha-2-macroglobulin family (A2M)	Alpha-2-macroglobulin family	-	Family
F, G	PF01759	UNC-6/NTR/C345C module (NTR)	UNC-6/NTR/C345C module	Sequence similarity between netrin UNC-6 and C345C complement protein family members, and hence the existence of the UNC-6 module, was first reported in [1]. Subsequently, many additional members of the family were identified on the basis of sequence ...	Sequence similarity between netrin UNC-6 and C345C complement protein family members, and hence the existence of the UNC-6 module, was first reported in [1]. Subsequently, many additional members of the family were identified on the basis of sequence similarity between the C-terminal domains of netrins, complement proteins C3, C4, C5, secreted frizzled-related proteins, and type I pro-collagen C-proteinase enhancer proteins (PCOLCEs), which are homologous with the N-terminal domains of tissue inhibitors of metalloproteinases (TIMPs). The TIMPs are classified as a separate family in Pfam (Pfam:PF00965) [2]. This expanded domain family has been named as the NTR module [2].	Domain
F, G	PF21406	Complement component 3, CUB domain, first segment (C3_CUB1)	Complement component 3, CUB domain, first segment	This entry represents the first segment of the CUB domain from complement component C3, which is completed but a second segment represented in Pfam:PF21308. The CUB domain is interrupted by the TE domain. The CUB domain forms a massive, tightly packe ...	This entry represents the first segment of the CUB domain from complement component C3, which is completed but a second segment represented in Pfam:PF21308. The CUB domain is interrupted by the TE domain. The CUB domain forms a massive, tightly packed super domain with the TE and MG8 domains [1-5]. These entry also includes venom factors, also known as Complement C3 homologues. These are complement-activating proteins with structural and functional similarities to complement component C3b, the activated form of C3 [6].	Domain
F, G	PF07678	A-macroglobulin TED domain (TED_complement)	A-macroglobulin TED domain	-	Repeat
F, G	PF07677	A-macroglobulin receptor binding domain (A2M_recep)	A-macroglobulin receptor binding domain	This family includes the receptor binding domain region of the alpha-2-macroglobulin family.	Domain
F, G	PF21308	Complement component 3, CUB domain, second segment (C3_CUB2)	Complement component 3, CUB domain, second segment	Complement C3 is major component in the both the classical and alternative complement activation pathways. C3 is cleaved into two chains (alpha and beta) by C3 convertases. This entry represents the second segment of the CUB domain, which is complete ...	Complement C3 is major component in the both the classical and alternative complement activation pathways. C3 is cleaved into two chains (alpha and beta) by C3 convertases. This entry represents the second segment of the CUB domain, which is completed by Pfam:PF21406 [2]. The CUB domain is interrupted by the TE domain. The CUB, TE and MG8 domains form a massive, tightly packed super domain. This entry also includes venom factors, also known as Complement C3 homologues. These are complement-activating proteins with structural and functional similarities to complement component C3b, the activated form of C3 [6].	Domain
F, G	PF07703	Alpha-2-macroglobulin bait region domain (A2M_BRD)	Alpha-2-macroglobulin bait region domain	Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and spe ...	Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and species that colonize higher eukaryotes. This domain is found in eukaryotic and bacterial proteins. In human A2Ms, this domain encompasses macroglobulin-like domain MG5 and 6 including bait region. In Salmonella enterica ser A2Ms, this domain encompasses MG7 and MG8 including the bait region [1] [2]. The Bait region is cleaved by proteases, followed by a large conformational change that blocks the target protease within a cage-like complex. This model of protease entrapment is recognised as the Venus flytrap mechanism [1].	Domain
F, G	PF17789	Macroglobulin domain MG4 (MG4)	Macroglobulin domain MG4	This domain is MG4 found in complement C3 and C5 proteins.	Domain
C [auth E]	PF00092	von Willebrand factor type A domain (VWA)	von Willebrand factor type A domain		Domain
C [auth E]	PF00089	Trypsin (Trypsin)	Trypsin		Domain
A, B [auth C], D [auth B]	PF21145	Complement C4, MG1 domain (C4_MG1)	Complement C4, MG1 domain	Complement component C4 is a non-enzymatic component of C3 and C5 convertases and essential for the propagation of the classical complement pathway. It covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune ...	Complement component C4 is a non-enzymatic component of C3 and C5 convertases and essential for the propagation of the classical complement pathway. It covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune aggregates and clearance through CR1 on erythrocytes. C4 is cleaved into the fragments C4a and C4b by MASP-2 protease. C4A isotype is responsible for effective binding to form amide bonds with immune aggregates or antigens, whereas C4B isotype catalyses the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens. This entry represents the macroglobulin 1 (MG1) domain found at the N-terminal of C4 [1].	Domain
A, B [auth C], D [auth B]	PF17791	Macroglobulin domain MG3 (MG3)	Macroglobulin domain MG3	This entry corresponds to the MG3 domain found in complement components C3, C4 and C5.	Domain
A, B [auth C], D [auth B]	PF01835	MG2 domain (MG2)	MG2 domain	This is the MG2 (macroglobulin) domain of alpha-2-macroglobulin in eukaryotes [1]. Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. How ...	This is the MG2 (macroglobulin) domain of alpha-2-macroglobulin in eukaryotes [1]. Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and species that colonize higher eukaryotes. This domain is found in eukaryotic and bacterial proteins. In human A2Ms, this domain is termed macroglobulin-like (MG) domain 2 and in Salmonella enterica ser A2Ms, this is domain 4 [2] [3].	Domain
A, B [auth C], D [auth B]	PF00207	Alpha-2-macroglobulin family (A2M)	Alpha-2-macroglobulin family	-	Family
A, B [auth C], D [auth B]	PF01759	UNC-6/NTR/C345C module (NTR)	UNC-6/NTR/C345C module	Sequence similarity between netrin UNC-6 and C345C complement protein family members, and hence the existence of the UNC-6 module, was first reported in [1]. Subsequently, many additional members of the family were identified on the basis of sequence ...	Sequence similarity between netrin UNC-6 and C345C complement protein family members, and hence the existence of the UNC-6 module, was first reported in [1]. Subsequently, many additional members of the family were identified on the basis of sequence similarity between the C-terminal domains of netrins, complement proteins C3, C4, C5, secreted frizzled-related proteins, and type I pro-collagen C-proteinase enhancer proteins (PCOLCEs), which are homologous with the N-terminal domains of tissue inhibitors of metalloproteinases (TIMPs). The TIMPs are classified as a separate family in Pfam (Pfam:PF00965) [2]. This expanded domain family has been named as the NTR module [2].	Domain
A, B [auth C], D [auth B]	PF22661	Complement C4A/B CUB C-terminal domain (CO4A-B_CUB_C)	Complement C4A/B CUB C-terminal domain	Complement C4 is organised in 12 structural domains, with eight macroglobulin (MG) domains forming the core of the molecule. They have a thioester domain (TED, Pfam:PF07678), a large helical domain inserted in the CUB (complement C1r/C1s, Uegf, Bmp1) ...	Complement C4 is organised in 12 structural domains, with eight macroglobulin (MG) domains forming the core of the molecule. They have a thioester domain (TED, Pfam:PF07678), a large helical domain inserted in the CUB (complement C1r/C1s, Uegf, Bmp1) domain [5] which consists of two antiparallel beta-sheets. This entry covers a fraction of the CUB domain corresponding to the C-terminal part (residues 1323-1389 in human C4A/B) as this domain is made up of residues located apart in these sequences [5].	Domain
A, B [auth C], D [auth B]	PF07678	A-macroglobulin TED domain (TED_complement)	A-macroglobulin TED domain	-	Repeat
A, B [auth C], D [auth B]	PF07677	A-macroglobulin receptor binding domain (A2M_recep)	A-macroglobulin receptor binding domain	This family includes the receptor binding domain region of the alpha-2-macroglobulin family.	Domain
A, B [auth C], D [auth B]	PF07703	Alpha-2-macroglobulin bait region domain (A2M_BRD)	Alpha-2-macroglobulin bait region domain	Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and spe ...	Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and species that colonize higher eukaryotes. This domain is found in eukaryotic and bacterial proteins. In human A2Ms, this domain encompasses macroglobulin-like domain MG5 and 6 including bait region. In Salmonella enterica ser A2Ms, this domain encompasses MG7 and MG8 including the bait region [1] [2]. The Bait region is cleaved by proteases, followed by a large conformational change that blocks the target protease within a cage-like complex. This model of protease entrapment is recognised as the Venus flytrap mechanism [1].	Domain
A, B [auth C], D [auth B]	PF17789	Macroglobulin domain MG4 (MG4)	Macroglobulin domain MG4	This domain is MG4 found in complement C3 and C5 proteins.	Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
F, G	Complement C3	enzyme regulator activity molecular function inhibitor activity peptidase regulator activity molecular function regulator activity enzyme inhibitor activity peptidase inhibitor activity endopeptidase regulator activity endopeptidase inhibitor activity C5L2 anaphylatoxin chemotactic receptor binding protein binding binding signaling receptor binding G protein-coupled receptor binding C5a anaphylatoxin chemotactic receptor binding enzyme regulator activity molecular function inhibitor activity peptidase regulator activity molecular function regulator activity enzyme inhibitor activity peptidase inhibitor activity endopeptidase regulator activity endopeptidase inhibitor activity C5L2 anaphylatoxin chemotactic receptor binding protein binding binding signaling receptor binding G protein-coupled receptor binding C5a anaphylatoxin chemotactic receptor binding molecular function activator activity signaling receptor regulator activity receptor ligand activity signaling receptor activator activity	cellular response to stimulus positive regulation of cell communication regulation of biological process regulation of signaling regulation of cellular process positive regulation of signal transduction response to stimulus signaling biological regulation positive regulation of biological process regulation of signal transduction positive regulation of G protein-coupled receptor signaling pathway cell communication positive regulation of response to stimulus regulation of response to stimulus cellular response to stimulus positive regulation of cell communication regulation of biological process regulation of signaling regulation of cellular process positive regulation of signal transduction response to stimulus signaling biological regulation positive regulation of biological process regulation of signal transduction positive regulation of G protein-coupled receptor signaling pathway cell communication positive regulation of response to stimulus regulation of response to stimulus regulation of cell communication G protein-coupled receptor signaling pathway cellular process signal transduction regulation of G protein-coupled receptor signaling pathway positive regulation of cellular process positive regulation of signaling neutral lipid metabolic process neutral lipid biosynthetic process regulation of triglyceride metabolic process regulation of lipid metabolic process lipid biosynthetic process regulation of primary metabolic process acylglycerol biosynthetic process triglyceride metabolic process triglyceride biosynthetic process regulation of biosynthetic process regulation of triglyceride biosynthetic process primary metabolic process biosynthetic process glycerolipid biosynthetic process metabolic process glycerolipid metabolic process regulation of lipid biosynthetic process acylglycerol metabolic process regulation of metabolic process lipid metabolic process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway immune response immunoglobulin mediated immune response adaptive immune response immune effector process immune system process B cell mediated immunity regulation of immune response activation of immune response developmental process multicellular organismal process cellular developmental process cell development developmental maturation nervous system development generation of neurons neurogenesis multicellular organism development neuron differentiation neuron remodeling anatomical structure maturation cell differentiation neuron development anatomical structure development neuron maturation cell maturation system development B cell activation cell activation lymphocyte activation leukocyte activation regulation of humoral immune response regulation of immune effector process positive regulation of humoral immune response positive regulation of complement activation positive regulation of immune effector process activation of membrane attack complex positive regulation of activation of membrane attack complex regulation of activation of membrane attack complex regulation of complement activation visual system development pattern specification process regionalization central nervous system development sensory system development vertebrate eye-specific patterning regulation of localization import into cell positive regulation of cellular component organization regulation of cellular component organization transport vesicle-mediated transport cellular component organization localization positive regulation of endocytosis cellular component organization or biogenesis positive regulation of receptor-mediated endocytosis regulation of endocytosis regulation of transport regulation of receptor-mediated endocytosis regulation of vesicle-mediated transport establishment of localization positive regulation of transport endocytosis receptor-mediated endocytosis biological process involved in interspecies interaction between organisms complement activation, alternative pathway response to biotic stimulus response to stress innate immune response response to external biotic stimulus response to other organism defense response defense response to symbiont response to external stimulus defense response to other organism epithelium development oviduct development reproductive system development oviduct epithelium development tube development reproductive process developmental process involved in reproduction tissue development reproductive structure development positive regulation of macromolecule biosynthetic process positive regulation of metabolic process positive regulation of biosynthetic process regulation of cytokine production cytokine production regulation of multicellular organismal process positive regulation of macromolecule metabolic process regulation of vascular endothelial growth factor production regulation of macromolecule metabolic process gene expression macromolecule biosynthetic process regulation of gene expression vascular endothelial growth factor production positive regulation of gene expression positive regulation of multicellular organismal process positive regulation of vascular endothelial growth factor production regulation of macromolecule biosynthetic process macromolecule metabolic process positive regulation of cytokine production positive regulation of membrane invagination regulation of phagocytosis, engulfment membrane invagination phagocytosis plasma membrane invagination membrane organization regulation of phagocytosis phagocytosis, engulfment positive regulation of phagocytosis positive regulation of phagocytosis, engulfment regulation of membrane invagination cellular component disassembly complement-mediated synapse pruning cell junction organization cell junction disassembly synapse pruning synapse organization immune response-regulating cell surface receptor signaling pathway complement receptor mediated signaling pathway immune response-activating signaling pathway immune response-regulating signaling pathway cell surface receptor signaling pathway immune response-activating cell surface receptor signaling pathway amyloid-beta clearance lipid storage lipid localization positive regulation of lipid localization regulation of lipid storage regulation of lipid localization macromolecule localization nutrient storage positive regulation of lipid storage fatty acid metabolic process oxoacid metabolic process carboxylic acid metabolic process small molecule metabolic process monocarboxylic acid metabolic process organic acid metabolic process positive regulation of acute inflammatory response to antigenic stimulus regulation of myeloid leukocyte mediated immunity regulation of acute inflammatory response to antigenic stimulus positive regulation of leukocyte mediated immunity regulation of type IIa hypersensitivity myeloid leukocyte mediated immunity inflammatory response to antigenic stimulus positive regulation of hypersensitivity positive regulation of inflammatory response positive regulation of adaptive immune response regulation of type II hypersensitivity positive regulation of immunoglobulin mediated immune response hypersensitivity regulation of adaptive immune response regulation of inflammatory response regulation of B cell mediated immunity regulation of leukocyte mediated immunity type II hypersensitivity positive regulation of myeloid leukocyte mediated immunity type IIa hypersensitivity positive regulation of defense response regulation of acute inflammatory response inflammatory response regulation of defense response regulation of response to external stimulus positive regulation of adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains positive regulation of lymphocyte mediated immunity positive regulation of acute inflammatory response positive regulation of B cell mediated immunity regulation of adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains positive regulation of response to external stimulus regulation of immunoglobulin mediated immune response regulation of response to stress acute inflammatory response regulation of hypersensitivity regulation of inflammatory response to antigenic stimulus acute inflammatory response to antigenic stimulus positive regulation of inflammatory response to antigenic stimulus positive regulation of type IIa hypersensitivity regulation of lymphocyte mediated immunity positive regulation of type II hypersensitivity complement activation, GZMK pathway regulation of developmental process angiogenesis regulation of vasculature development positive regulation of developmental process tube morphogenesis regulation of anatomical structure morphogenesis blood vessel development regulation of multicellular organismal development blood vessel morphogenesis positive regulation of angiogenesis vasculature development circulatory system development anatomical structure morphogenesis positive regulation of vasculature development regulation of angiogenesis anatomical structure formation involved in morphogenesis response to bacterium complement-dependent cytotoxicity cell killing positive regulation of phosphorylation regulation of protein modification process regulation of protein phosphorylation positive regulation of protein metabolic process positive regulation of phosphate metabolic process positive regulation of protein modification process phosphate-containing compound metabolic process protein metabolic process positive regulation of protein phosphorylation phosphorus metabolic process protein modification process protein phosphorylation positive regulation of phosphorus metabolic process phosphorylation regulation of protein metabolic process macromolecule modification regulation of phosphorus metabolic process regulation of phosphorylation positive regulation of apoptotic cell clearance apoptotic cell clearance regulation of apoptotic cell clearance hexose transmembrane transport carbohydrate transport positive regulation of D-glucose transmembrane transport transmembrane transport regulation of transmembrane transport D-glucose transmembrane transport positive regulation of transmembrane transport regulation of D-glucose transmembrane transport monosaccharide transmembrane transport carbohydrate transmembrane transport	extracellular exosome membrane-bounded organelle extracellular vesicle cellular anatomical structure extracellular organelle extracellular region organelle extracellular space vesicle extracellular membrane-bounded organelle intracellular anatomical structure membrane-enclosed lumen intracellular membrane-bounded organelle endomembrane system extracellular exosome membrane-bounded organelle extracellular vesicle cellular anatomical structure extracellular organelle extracellular region organelle extracellular space vesicle extracellular membrane-bounded organelle intracellular anatomical structure membrane-enclosed lumen intracellular membrane-bounded organelle endomembrane system intracellular organelle lumen endoplasmic reticulum lumen intracellular organelle organelle lumen endoplasmic reticulum cytoplasm cell surface cell periphery plasma membrane membrane lytic vacuole intracellular vesicle cytoplasmic vesicle lumen vacuolar lumen cytoplasmic vesicle lysosome vesicle lumen azurophil granule vacuole secretory granule lumen azurophil granule lumen secretory granule primary lysosome secretory vesicle protein-containing complex blood microparticle
E [auth D]	Anti-C4b nanobody B12	-	-	-
C [auth E]	Complement C2	peptidase activity catalytic activity, acting on a protein serine hydrolase activity serine-type peptidase activity hydrolase activity serine-type endopeptidase activity catalytic activity endopeptidase activity cation binding ion binding binding metal ion binding small molecule binding	adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process immune response biological regulation immunoglobulin mediated immune response adaptive immune response immune effector process regulation of response to stimulus immune system process B cell mediated immunity regulation of immune response activation of immune response biological process involved in interspecies interaction between organisms response to biotic stimulus response to stress innate immune response response to external biotic stimulus response to other organism defense response defense response to symbiont response to external stimulus complement activation, GZMK pathway defense response to other organism response to thyroid hormone response to hormone response to endogenous stimulus response to chemical response to bacterium import into cell regulation of localization positive regulation of cellular component organization regulation of cellular process regulation of cellular component organization transport positive regulation of apoptotic cell clearance vesicle-mediated transport cellular component organization localization positive regulation of endocytosis phagocytosis apoptotic cell clearance cellular component organization or biogenesis positive regulation of cellular process regulation of endocytosis regulation of transport regulation of phagocytosis regulation of vesicle-mediated transport establishment of localization positive regulation of phagocytosis positive regulation of transport cellular process endocytosis regulation of apoptotic cell clearance response to nutrient levels response to nutrient proteolysis metabolic process primary metabolic process protein metabolic process macromolecule metabolic process response to lipid response to oxygen-containing compound response to lipopolysaccharide response to molecule of bacterial origin	extracellular exosome membrane-bounded organelle extracellular vesicle cellular anatomical structure extracellular organelle extracellular region organelle extracellular space vesicle extracellular membrane-bounded organelle cell surface other organism part symbiont cell surface
A, B [auth C], D [auth B]	Complement C4-A	complement component C1q complex binding opsonin binding protein-containing complex binding protein binding binding complement binding enzyme regulator activity molecular function inhibitor activity peptidase regulator activity molecular function regulator activity enzyme inhibitor activity peptidase inhibitor activity endopeptidase regulator activity endopeptidase inhibitor activity	adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process immune response biological regulation immunoglobulin mediated immune response adaptive immune response immune effector process regulation of response to stimulus immune system process B cell mediated immunity regulation of immune response activation of immune response biological process involved in interspecies interaction between organisms response to biotic stimulus response to stress innate immune response response to external biotic stimulus response to other organism defense response defense response to symbiont response to external stimulus complement activation, GZMK pathway defense response to other organism inflammatory response import into cell regulation of localization positive regulation of cellular component organization regulation of cellular process regulation of cellular component organization transport positive regulation of apoptotic cell clearance vesicle-mediated transport cellular component organization localization positive regulation of endocytosis phagocytosis apoptotic cell clearance cellular component organization or biogenesis positive regulation of cellular process regulation of endocytosis regulation of transport regulation of phagocytosis regulation of vesicle-mediated transport establishment of localization positive regulation of phagocytosis positive regulation of transport cellular process endocytosis regulation of apoptotic cell clearance	extracellular exosome membrane-bounded organelle extracellular vesicle cellular anatomical structure extracellular organelle extracellular region organelle extracellular space vesicle extracellular membrane-bounded organelle cell surface cell periphery plasma membrane membrane extracellular exosome membrane-bounded organelle extracellular vesicle cellular anatomical structure extracellular organelle extracellular region organelle extracellular space vesicle extracellular membrane-bounded organelle cell surface cell periphery plasma membrane membrane somatodendritic compartment cell projection dendrite dendritic tree neuron projection plasma membrane bounded cell projection blood microparticle intracellular anatomical structure membrane-enclosed lumen intracellular membrane-bounded organelle endomembrane system intracellular organelle lumen endoplasmic reticulum lumen intracellular organelle organelle lumen endoplasmic reticulum cytoplasm synapse cell junction cell body neuronal cell body axon

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
F, G	IPR019742	Alpha-2-macroglobulin, conserved site	Conserved Site
F, G	IPR009048	Alpha-macroglobulin, receptor-binding	Domain
F, G	IPR049466	Complement component 3, CUB domain, first segment	Domain
F, G	IPR001599	Alpha-2-macroglobulin	Domain
F, G	IPR001134	Netrin domain	Domain
F, G	IPR011626	Alpha-macroglobulin-like, TED domain	Domain
F, G	IPR002890	Macroglobulin domain	Domain
F, G	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
F, G	IPR008930	Terpenoid cyclases/protein prenyltransferase alpha-alpha toroid	Homologous Superfamily
F, G	IPR041555	Macroglobulin domain MG3	Domain
F, G	IPR047565	Alpha-macroglobulin-like, thiol-ester bond-forming region	Conserved Site
F, G	IPR048848	Complement component 3, CUB domain, second segment	Domain
F, G	IPR018081	Anaphylatoxin, complement system	Homologous Superfamily
F, G	IPR035815	Complement C3-like, NTR domain	Domain
F, G	IPR018933	Netrin module, non-TIMP type	Domain
F, G	IPR001840	Anaphylatoxin, complement system domain	Domain
F, G	IPR041425	Complement C3/4/5, macroglobulin domain MG1	Domain
F, G	IPR011625	Alpha-2-macroglobulin, bait region domain	Domain
F, G	IPR008993	Tissue inhibitor of metalloproteinases-like, OB-fold	Homologous Superfamily
F, G	IPR000020	Anaphylatoxin/fibulin	Domain
F, G	IPR036595	Alpha-macroglobulin, receptor-binding domain superfamily	Homologous Superfamily
F, G	IPR050473	Alpha-2-macroglobulin/Complement system	Family
F, G	IPR040839	Macroglobulin domain MG4	Domain
C [auth E]	IPR011360	Complement B/C2	Family
C [auth E]	IPR000436	Sushi/SCR/CCP domain	Domain
C [auth E]	IPR018114	Serine proteases, trypsin family, histidine active site	Active Site
C [auth E]	IPR043504	Peptidase_S1_PA_chymotrypsin	Unknown
C [auth E]	IPR035976	Sushi/SCR/CCP superfamily	Homologous Superfamily
C [auth E]	IPR009003	Peptidase S1, PA clan	Homologous Superfamily
C [auth E]	IPR036465	von Willebrand factor A-like domain superfamily	Homologous Superfamily
C [auth E]	IPR001314	Peptidase S1A, chymotrypsin family	Family
C [auth E]	IPR033116	Serine proteases, trypsin family, serine active site	Active Site
C [auth E]	IPR001254	Serine proteases, trypsin domain	Domain
C [auth E]	IPR002035	von Willebrand factor, type A	Domain
A, B [auth C], D [auth B]	IPR019742	Alpha-2-macroglobulin, conserved site	Conserved Site
A, B [auth C], D [auth B]	IPR009048	Alpha-macroglobulin, receptor-binding	Domain
A, B [auth C], D [auth B]	IPR041555	Macroglobulin domain MG3	Domain
A, B [auth C], D [auth B]	IPR001599	Alpha-2-macroglobulin	Domain
A, B [auth C], D [auth B]	IPR047565	Alpha-macroglobulin-like, thiol-ester bond-forming region	Conserved Site
A, B [auth C], D [auth B]	IPR018081	Anaphylatoxin, complement system	Homologous Superfamily
A, B [auth C], D [auth B]	IPR018933	Netrin module, non-TIMP type	Domain
A, B [auth C], D [auth B]	IPR001840	Anaphylatoxin, complement system domain	Domain
A, B [auth C], D [auth B]	IPR011625	Alpha-2-macroglobulin, bait region domain	Domain
A, B [auth C], D [auth B]	IPR001134	Netrin domain	Domain
A, B [auth C], D [auth B]	IPR008993	Tissue inhibitor of metalloproteinases-like, OB-fold	Homologous Superfamily
A, B [auth C], D [auth B]	IPR011626	Alpha-macroglobulin-like, TED domain	Domain
A, B [auth C], D [auth B]	IPR000020	Anaphylatoxin/fibulin	Domain
A, B [auth C], D [auth B]	IPR036595	Alpha-macroglobulin, receptor-binding domain superfamily	Homologous Superfamily
A, B [auth C], D [auth B]	IPR002890	Macroglobulin domain	Domain
A, B [auth C], D [auth B]	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
A, B [auth C], D [auth B]	IPR050473	Alpha-2-macroglobulin/Complement system	Family
A, B [auth C], D [auth B]	IPR008930	Terpenoid cyclases/protein prenyltransferase alpha-alpha toroid	Homologous Superfamily
A, B [auth C], D [auth B]	IPR048847	Complement C4, MG1 domain	Domain
A, B [auth C], D [auth B]	IPR054587	Complement C4A/B, CUB C-terminal domain	Domain
A, B [auth C], D [auth B]	IPR040839	Macroglobulin domain MG4	Domain

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
F, G	Pharos: P01024	complement component 3 deficiency age-related macular degeneration Henoch-Schoenlein purpura atypical hemolytic-uremic syndrome pemphigus age related macular degeneration 9 membranous glomerulonephritis Insulin Resistance pemphigus vulgaris transient ischemic attack atypical hemolytic-uremic syndrome with C3 anomaly primary immunodeficiency disease middle cerebral artery infarction type 2 diabetes mellitus hemolytic-uremic syndrome complement component 3 deficiency age-related macular degeneration Henoch-Schoenlein purpura atypical hemolytic-uremic syndrome pemphigus age related macular degeneration 9 membranous glomerulonephritis Insulin Resistance pemphigus vulgaris transient ischemic attack atypical hemolytic-uremic syndrome with C3 anomaly primary immunodeficiency disease middle cerebral artery infarction type 2 diabetes mellitus hemolytic-uremic syndrome paratuberculosis chronic kidney disease juvenile dermatomyositis congestive heart failure large cell medulloblastoma cystic fibrosis lung cancer malignant colon neoplasm acquired paroxysmal nocturnal hemoglobinuria subependymal giant cell astrocytoma maturity-onset diabetes of the young tuberculosis Emery-Dreifuss muscular dystrophy Gaucher disease hemolytic anemia non-small cell lung carcinoma pancreatic intraductal papillary-mucinous carcinoma Becker muscular dystrophy periodontitis chronic obstructive pulmonary disease kidney disease dermatomyositis lung carcinoma Down syndrome malignant ependymoma acute kidney failure medulloblastoma adenoma Duchenne muscular dystrophy Finnish type amyloidosis astrocytic tumor wet macular degeneration glioblastoma ovarian cancer atypical teratoid rhabdoid tumor pancreatic intraductal papillary-mucinous neoplasm with low grade dysplasia idiopathic membranous glomerulonephritis pemphigus foliaceus invasive ductal breast carcinoma pilocytic astrocytoma psoriasis Creutzfeldt Jacob disease limb-girdle muscular dystrophy retinal degeneration diabetes mellitus macular degeneration Sjogren syndrome malignant mesothelioma drug-induced liver injury adrenal cortex carcinoma ulcerative colitis gastric carcinoma myopathy head and neck cancer pancreatic ductal adenocarcinoma autoimmune disease
C [auth E]	Pharos: P06681	complement component 2 deficiency age-related macular degeneration IgA glomerulonephritis dermatomyositis irritant dermatitis MACULAR DEGENERATION, AGE-RELATED, 14 neuromyelitis optica psoriatic arthritis squamous cell lung carcinoma ulcerative colitis autism spectrum disorder Crohn disease endometriosis heart disease lung carcinoma complement component 2 deficiency age-related macular degeneration IgA glomerulonephritis dermatomyositis irritant dermatitis MACULAR DEGENERATION, AGE-RELATED, 14 neuromyelitis optica psoriatic arthritis squamous cell lung carcinoma ulcerative colitis autism spectrum disorder Crohn disease endometriosis heart disease lung carcinoma non-alcoholic fatty liver disease retinal degeneration subependymal giant cell astrocytoma age related macular degeneration 14 vitiligo cervical cancer eosinophilic esophagitis hepatitis B virus infection macular degeneration membranous glomerulonephritis non-small cell lung carcinoma skin basal cell carcinoma systemic lupus erythematosus wet macular degeneration Hashimoto thyroiditis hypertensive disorder juvenile dermatomyositis
A, B [auth C], D [auth B]	Pharos: P0C0L4	systemic lupus erythematosus complement component 4a deficiency primary immunodeficiency disease sarcoidosis age-related macular degeneration autism spectrum disorder cervical cancer endometriosis hepatitis B virus infection membranous glomerulonephritis schizophrenia ulcerative colitis Antibody Deficiency Syndrome autosomal systemic lupus erythematosus type 16 Hashimoto thyroiditis systemic lupus erythematosus complement component 4a deficiency primary immunodeficiency disease sarcoidosis age-related macular degeneration autism spectrum disorder cervical cancer endometriosis hepatitis B virus infection membranous glomerulonephritis schizophrenia ulcerative colitis Antibody Deficiency Syndrome autosomal systemic lupus erythematosus type 16 Hashimoto thyroiditis lung carcinoma neuromyelitis optica psoriatic arthritis squamous cell lung carcinoma wet macular degeneration atopic eczema Behcet disease complement component 4b deficiency heart disease lupus erythematosus non-alcoholic fatty liver disease