2Q20 | pdb_00002q20

Structure of the germline Vk1 O18/O8 light chain variable domain homodimer

External Resource: Annotation

Domain Annotation: SCOP/SCOPe Classification
Domain Annotation: ECOD Classification
Domain Annotation: CATH
SAbDab Antibody Annotation
Protein Family Annotation
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification

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

Chains	Domain Info	Class	Fold	Superfamily	Family	Domain	Species	Provenance Source (Version)
B	d2q20b_	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	V set domains (antibody variable domain-like)	automated matches	human (Homo sapiens ) [TaxId: 9606 ],	SCOPe (2.08)
A	d2q20a_	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	V set domains (antibody variable domain-like)	automated matches	human (Homo sapiens ) [TaxId: 9606 ],	SCOPe (2.08)

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
B	TetR_N	e2q20B1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: TetR_N	ECOD (v294.1)
A	Response_reg	e2q20A1	A: a/b three-layered sandwiches	X: Profilin-like	H: sensor domains	T: sensor domains	F: Response_reg	ECOD (v294.1)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
B	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
A	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
A, B	Light Chain	IGKV1	Kappa	-	SAbDab (2026-03-27)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, B	PF07686	Immunoglobulin V-set domain (V-set)	Immunoglobulin V-set domain	This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.	Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A, B	Vk1 O18/O8 germline light chain variable domain	identical protein binding protein binding binding antigen binding	response to stimulus immune response immune system process adaptive immune response	cellular anatomical structure extracellular region extracellular space blood microparticle cell periphery plasma membrane membrane protein-containing complex immunoglobulin complex

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, B	IPR050150	Immunoglobulin Variable Light Chain	Family
A, B	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
A, B	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
A, B	IPR013106	Immunoglobulin V-set domain	Domain
A, B	IPR003599	Immunoglobulin domain subtype	Domain
A, B	IPR007110	Immunoglobulin-like domain	Domain

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. RCSB PDB uses resources of the National Energy Research Scientific Computing Center (NERSC), a Department of Energy User Facility.