Annotations: 4KAQ

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

Chains	Domain Info	Class	Fold	Superfamily	Family	Domain	Species	Provenance Source (Version)
A [auth L]	d4kaql2	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	C1 set domains (antibody constant domain-like)	automated matches	human (Homo sapiens ) [TaxId: 9606 ], house mouse (Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
A [auth L]	d4kaql1	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	automated matches	automated matches	human (Homo sapiens ) [TaxId: 9606 ], house mouse (Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
B [auth H]	d4kaqh_	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	automated matches	automated matches	human (Homo sapiens ) [TaxId: 9606 ], house mouse (Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A [auth L]		e4kaqL1	A: alpha bundles	X: P-loop domains-like	H: P-loop domains-related	T: P-loop containing nucleoside triphosphate hydrolases	F:	ECOD (develop294)
B [auth H]		e4kaqH1	A: alpha bundles	X: P-loop domains-like	H: P-loop domains-related	T: P-loop containing nucleoside triphosphate hydrolases	F:	ECOD (develop294)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
A [auth L]	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
B [auth H]	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
A [auth L]	IDEC-C2B8	L-KAPPA	-	IGKV4-7201, IGKJ101, IGKJ201, IGKC01	V-DOMAIN V-KAPPA, C-DOMAIN C-KAPPA	IG	FAB-GAMMA-1_KAPPA	IMGT (202610-0)
B [auth H]	IDEC-C2B8	VH-CH1	-	IGHV1-1201, IGHJ101, IGHJ102, IGHG101, IGHG102, IGHG104	V-DOMAIN VH, C-DOMAIN CH1	IG	FAB-GAMMA-1_KAPPA	IMGT (202610-0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
A [auth L]	Light Chain	IGKV4	Kappa	-	SAbDab (2026-03-20)
B [auth H]	Heavy Chain	IGHV1	-	-	SAbDab (2026-03-20)

Thera-SAbDab Antibody Annotation Thera-SAbDab Database Homepage

Chain	Name	Target	Provenance Source
A [auth L]	Rituximab	MS4A1/CD20	Therapeutic SAbDab (2026-03-20)
B [auth H]	Amulirafusp	MS4A1/CD20	Therapeutic SAbDab (2026-03-20)

Protein Modification Annotation

Modified Residue(s)
Chain	Residue(s)	Description
B [auth H]	PCA	Parent Component: GLN RESID: AA0031 PSI-MOD : 2-pyrrolidone-5-carboxylic acid (Gln) MOD:00040 , 2-pyrrolidone-5-carboxylic acid (Glu) MOD:00420

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.