1K4C | pdb_00001k4c

Potassium Channel KcsA-Fab complex in high concentration of K+

External Resource: Annotation

Domain Annotation: SCOP/SCOPe Classification
Domain Annotation: SCOP2 Classification
Domain Annotation: ECOD Classification
Domain Annotation: CATH
IMGT Antibody Annotation
SAbDab Antibody Annotation
Protein Family Annotation
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification
Membrane Protein Annotation: PDBTM
Membrane Protein Annotation: MemProtMD
Membrane Protein Annotation: mpstruc

Domain Annotation: SCOP/SCOPe Classification SCOP-e Database Homepage

Chains	Domain Info	Class	Fold	Superfamily	Family	Domain	Species	Provenance Source (Version)
A	d1k4ca1	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	V set domains (antibody variable domain-like)	Immunoglobulin heavy chain variable domain, VH	(Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
A	d1k4ca2	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	C1 set domains (antibody constant domain-like)	Immunoglobulin heavy chain gamma constant domain 1, CH1-gamma	(Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
A	d1k4ca3	Artifacts	Tags	Tags	Tags	N-terminal Tags	(Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
B	d1k4cb1	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	V set domains (antibody variable domain-like)	Immunoglobulin light chain kappa variable domain, VL-kappa	(Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
B	d1k4cb2	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	C1 set domains (antibody constant domain-like)	Immunoglobulin light chain kappa constant domain, CL-kappa	(Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
C	d1k4cc_	Membrane and cell surface proteins and peptides	Gated ion channels	Voltage-gated ion channels	Voltage-gated potassium channels	Potassium channel protein	(Streptomyces lividans ) [TaxId: 1916 ],	SCOPe (2.08)

Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

Chains	Type	Family Name	Domain Identifier	Family Identifier	Provenance Source (Version)
B	SCOP2B Superfamily	Immunoglobulin (Ig) domain-like	8091539	3000071	SCOP2B (2022-06-29)
C	SCOP2B Superfamily	Voltage-gated potassium channels	8003437	3000023	SCOP2B (2022-06-29)

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A	V-set_8	e1k4cA1	A: beta sandwiches	X: Immunoglobulin-like beta-sandwich	H: Immunoglobulin-related	T: Immunoglobulin/Fibronectin type III/E set domains/PapD-like	F: V-set_8	ECOD (1.6)
A	C1-set_1	e1k4cA2	A: beta sandwiches	X: Immunoglobulin-like beta-sandwich	H: Immunoglobulin-related	T: Immunoglobulin/Fibronectin type III/E set domains/PapD-like	F: C1-set_1	ECOD (1.6)
B	C1-set_4	e1k4cB2	A: beta sandwiches	X: Immunoglobulin-like beta-sandwich	H: Immunoglobulin-related	T: Immunoglobulin/Fibronectin type III/E set domains/PapD-like	F: C1-set_4	ECOD (1.6)
B	V-set	e1k4cB1	A: beta sandwiches	X: Immunoglobulin-like beta-sandwich	H: Immunoglobulin-related	T: Immunoglobulin/Fibronectin type III/E set domains/PapD-like	F: V-set	ECOD (1.6)
C	Ion_trans_2	e1k4cC1	A: alpha complex topology	X: Voltage-gated ion channels (From Topology)	H: Voltage-gated ion channels (From Topology)	T: Voltage-gated ion channels	F: Ion_trans_2	ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
A	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
B	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
C	1.10.287.70	Mainly Alpha	Orthogonal Bundle	Helix Hairpins		CATH (4.3.0)

IMGT Antibody Annotation IMGT Database Homepage

Chain	Protein Name	Description	Organism Name	Gene Allele Name(s)	Domain Name(s)	Receptor Type	Receptor Description	Provenance Source
A	Antibody Fab Fragment	VH-CH1	Mus musculus (house mouse)	IGHV1S8102, IGHJ101, IGHJ102, IGHG102	V-DOMAIN VH, C-DOMAIN CH1	IG	FAB-GAMMA-1_KAPPA	IMGT (202541-0)
B	Antibody Fab Fragment	L-KAPPA	Mus musculus (house mouse)	IGKV5-4801, IGKJ401, IGKC01, IGKC02	V-DOMAIN V-KAPPA, C-DOMAIN C-KAPPA	IG	FAB-GAMMA-1_KAPPA	IMGT (202541-0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
A	Heavy Chain	IGHV1	-	potassium channel kcsa	SAbDab (2025-10-24)
B	Light Chain	IGKV5	Kappa	potassium channel kcsa	SAbDab (2025-10-24)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
B	PF07654	Immunoglobulin C1-set domain (C1-set)	Immunoglobulin C1-set domain		Domain
C	PF07885	Ion channel (Ion_trans_2)	Ion channel	-	Family
C	PF00520	Ion transport protein (Ion_trans)	Ion transport protein	-	Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A	antibody Fab fragment heavy chain	-	-	-
B	antibody Fab fragment light chain	-	developmental process multicellular organismal process cellular developmental process hemopoiesis B cell activation cell activation cell development mononuclear cell differentiation lymphocyte differentiation lymphocyte activation leukocyte activation B cell differentiation cell differentiation immune system process anatomical structure development developmental process multicellular organismal process cellular developmental process hemopoiesis B cell activation cell activation cell development mononuclear cell differentiation lymphocyte differentiation lymphocyte activation leukocyte activation B cell differentiation cell differentiation immune system process anatomical structure development cellular process leukocyte differentiation	cell periphery cellular anatomical structure plasma membrane membrane extracellular region
C	potassium channel KcsA	monoatomic cation transmembrane transporter activity gated channel activity monoatomic ion channel activity potassium ion transmembrane transporter activity voltage-gated channel activity voltage-gated monoatomic ion channel activity potassium channel activity voltage-gated monoatomic cation channel activity monoatomic cation channel activity passive transmembrane transporter activity voltage-gated potassium channel activity channel activity monoatomic ion transmembrane transporter activity transporter activity metal ion transmembrane transporter activity monoatomic cation transmembrane transporter activity gated channel activity monoatomic ion channel activity potassium ion transmembrane transporter activity voltage-gated channel activity voltage-gated monoatomic ion channel activity potassium channel activity voltage-gated monoatomic cation channel activity monoatomic cation channel activity passive transmembrane transporter activity voltage-gated potassium channel activity channel activity monoatomic ion transmembrane transporter activity transporter activity metal ion transmembrane transporter activity transmembrane transporter activity identical protein binding protein binding binding	biological regulation action potential regulation of biological quality regulation of membrane potential	voltage-gated potassium channel complex protein-containing complex plasma membrane protein complex membrane plasma membrane potassium channel complex membrane protein complex cation channel complex transporter complex cell periphery cellular anatomical structure transmembrane transporter complex monoatomic ion channel complex

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
B	IPR003597	Immunoglobulin C1-set	Domain
B	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
B	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
B	IPR007110	Immunoglobulin-like domain	Domain
B	IPR050380	Immune Recognition and Response Modulators	Family
B	IPR003006	Immunoglobulin/major histocompatibility complex, conserved site	Conserved Site
C	IPR013099	Potassium channel domain	Domain
C	IPR028325	Voltage-gated potassium channel	Family

Membrane Protein Annotation: PDBTM PDBTM Database Homepage

Chains	External Link	Comment
C	PDBTM	Annotated as membrane protein by PDBTM

Membrane Protein Annotation: MemProtMD MemProtMD Database Homepage

Chains	External Link	Comment
C	MemProtMD	Annotated as membrane protein by MemProtMD

Membrane Protein Annotation: mpstruc mpstruc Database Homepage

Chains	Resource Link	Group	Subgroup	Protein
C	mpstruc	TRANSMEMBRANE PROTEINS: ALPHA-HELICAL	Channels: Potassium, Sodium, & Proton Ion-Selective	KcsA Potassium channel, H⁺ gated. Complexed with Fab.

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM157729.