Annotations: 4LKX

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
B	PolyA_pol	e4lkxB1	A: a/b three-layered sandwiches	X: Thioredoxin-like	H: Thioredoxin-like	T: Thioredoxin-like	F: PolyA_pol	ECOD (v294.1)
A	PolyA_pol	e4lkxA1	A: a/b three-layered sandwiches	X: Thioredoxin-like	H: Thioredoxin-like	T: Thioredoxin-like	F: PolyA_pol	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)

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
B	FAB FRAGMENT LIGHT CHAIN	L-KAPPA	Homo sapiens (human)	IGKV2-2902, IGKV2-2903, IGKJ401, IGKJ402, IGKC*01	V-DOMAIN V-KAPPA, C-DOMAIN C-KAPPA	IG	FAB-GAMMA-1_KAPPA	IMGT (202613-0)
A	FAB FRAGMENT LIGHT CHAIN	VH-CH1	Homo sapiens (human)	IGHV4-38-202, IGHJ401, IGHJ402, IGHJ403, IGHG101, IGHG102, IGHG1*04	V-DOMAIN VH, C-DOMAIN CH1	IG	FAB-GAMMA-1_KAPPA	IMGT (202613-0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
B	Light Chain	IGKV1	Kappa	cemx segment	SAbDab (2026-04-10)
A	Heavy Chain	IGHV4	-	cemx segment	SAbDab (2026-04-10)

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
C [auth R]	CemX segment	-	-	-
B	Fab fragment light chain	-	response to stimulus immune response immune system process adaptive immune response	cell periphery cellular anatomical structure plasma membrane membrane protein-containing complex immunoglobulin complex extracellular region
A	Fab fragment heavy chain	-	response to stimulus immune response immune system process adaptive immune response	cell periphery cellular anatomical structure plasma membrane membrane protein-containing complex immunoglobulin complex extracellular region

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
B	IPR003597	Immunoglobulin C1-set	Domain
B	IPR050150	Immunoglobulin Variable Light Chain	Family
B	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
B	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
B	IPR013106	Immunoglobulin V-set domain	Domain
B	IPR003599	Immunoglobulin domain subtype	Domain
B	IPR007110	Immunoglobulin-like domain	Domain
B	IPR003006	Immunoglobulin/major histocompatibility complex, conserved site	Conserved Site
A	IPR003597	Immunoglobulin C1-set	Domain
A	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
A	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
A	IPR013106	Immunoglobulin V-set domain	Domain
A	IPR003599	Immunoglobulin domain subtype	Domain
A	IPR007110	Immunoglobulin-like domain	Domain
A	IPR050380	Immune Recognition and Response Modulators	Family
A	IPR003006	Immunoglobulin/major histocompatibility complex, conserved site	Conserved Site

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.