Annotations: 3CM9

Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

Chains	Type	Family Name	Domain Identifier	Family Identifier	Provenance Source (Version)
J [auth S]	SCOP2B Superfamily	Immunoglobulin (Ig) domain-like	8054529	3000071	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	IL7	e3cm9A1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
A	P-loop_SecA	e3cm9A3	A: a/b three-layered sandwiches	X: jelly-roll	H: Double-stranded beta-helix	T: Double-stranded beta-helix	F: P-loop_SecA	ECOD (v294.1)
B	IL7	e3cm9B1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
B	P-loop_SecA	e3cm9B3	A: a/b three-layered sandwiches	X: jelly-roll	H: Double-stranded beta-helix	T: Double-stranded beta-helix	F: P-loop_SecA	ECOD (v294.1)
C	IL7	e3cm9C1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
C	P-loop_SecA	e3cm9C3	A: a/b three-layered sandwiches	X: jelly-roll	H: Double-stranded beta-helix	T: Double-stranded beta-helix	F: P-loop_SecA	ECOD (v294.1)
D	IL7	e3cm9D1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
D	P-loop_SecA	e3cm9D3	A: a/b three-layered sandwiches	X: jelly-roll	H: Double-stranded beta-helix	T: Double-stranded beta-helix	F: P-loop_SecA	ECOD (v294.1)
E [auth J]	IL7	e3cm9J1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
F [auth L]	IL7	e3cm9L1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
G [auth M]	IL7	e3cm9M1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
H [auth N]	IL7	e3cm9N1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)
I [auth O]	IL7	e3cm9O1	A: a/b three-layered sandwiches	X: HTH	H: Nudix	T: Nudix	F: IL7	ECOD (v294.1)

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, B, C, D	SIgA2	H-ALPHA-2	Homo sapiens (human)	IGHV1-301, IGHJ401, IGHJ402, IGHJ403, IGHA2*01	V-DOMAIN VH, C-DOMAIN CH1, C-DOMAIN CH2, C-DOMAIN CH3	IG	IG-ALPHA-2_KAPPA	IMGT (202612-0)
E [auth J]	PIGR (Polymeric immunoglobulin receptor)	1V-LIKE	Homo sapiens (human)	PIGR	V-LIKE-DOMAIN V-LIKE	RPI	(1V-LIKE_5V-LIKE)	IMGT (202612-0)
F [auth L], G [auth M], H [auth N], I [auth O]	SIgA2	L-KAPPA	Homo sapiens (human)	IGKV1-1302, IGKV1D-1302, IGKJ401, IGKJ402, IGKC*01	V-DOMAIN V-KAPPA, C-DOMAIN C-KAPPA	IG	IG-ALPHA-2_KAPPA	IMGT (202612-0)
J [auth S]	PIGR (Polymeric immunoglobulin receptor)	5V-LIKE	Homo sapiens (human)	PIGR	V-LIKE-DOMAIN V-LIKE	RPI	(1V-LIKE_5V-LIKE)	IMGT (202612-0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
A, B, C, D	Heavy Chain	IGHV1	-	-	SAbDab (2026-03-27)
F [auth L], G [auth M], H [auth N], I [auth O]	Light Chain	IGKV1	Kappa	-	SAbDab (2026-03-27)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, B, C, D	PF07654	Immunoglobulin C1-set domain (C1-set)	Immunoglobulin C1-set domain		Domain
A, B, C, D	PF00047	Immunoglobulin domain (ig)	Immunoglobulin domain	Members of the immunoglobulin superfamily are found in hundreds of proteins of different functions. Examples include antibodies, the giant muscle kinase titin and receptor tyrosine kinases. Immunoglobulin-like domains may be involved in protein-prote ...	Members of the immunoglobulin superfamily are found in hundreds of proteins of different functions. Examples include antibodies, the giant muscle kinase titin and receptor tyrosine kinases. Immunoglobulin-like domains may be involved in protein-protein and protein-ligand interactions.	Domain
E [auth J]	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
J [auth S]	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, C, D	Immunoglobulin heavy chain	binding antigen binding	cellular response to stimulus immune response-regulating cell surface receptor signaling pathway regulation of cellular process response to stimulus signaling positive regulation of biological process cell communication positive regulation of response to stimulus immune response-activating signaling pathway immune response-regulating signaling pathway positive regulation of immune response regulation of immune system process signal transduction positive regulation of immune system process cellular response to stimulus immune response-regulating cell surface receptor signaling pathway regulation of cellular process response to stimulus signaling positive regulation of biological process cell communication positive regulation of response to stimulus immune response-activating signaling pathway immune response-regulating signaling pathway positive regulation of immune response regulation of immune system process signal transduction positive regulation of immune system process regulation of biological process cell surface receptor signaling pathway immune response-activating cell surface receptor signaling pathway immune response B cell receptor signaling pathway biological regulation regulation of response to stimulus immune system process regulation of immune response cellular process antigen receptor-mediated signaling pathway activation of immune response adaptive immune response 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 leukocyte mediated immunity complement activation, classical pathway immunoglobulin mediated immune response immune effector process B cell mediated immunity biological process involved in interspecies interaction between organisms response to other organism defense response antibacterial humoral response defense response to symbiont response to external stimulus antimicrobial humoral response response to biotic stimulus defense response to bacterium defense response to other organism response to stress response to bacterium response to external biotic stimulus multicellular organismal process renal system process system process glomerular filtration renal filtration positive regulation of respiratory burst positive regulation of metabolic process respiratory burst metabolic process regulation of respiratory burst regulation of metabolic process positive regulation of cellular process	protein-containing complex IgA immunoglobulin complex immunoglobulin complex IgA immunoglobulin complex, circulating cellular anatomical structure secretory IgA immunoglobulin complex extracellular region extracellular protein-containing complex polymeric IgA immunoglobulin complex immunoglobulin complex, circulating extracellular exosome membrane-bounded organelle extracellular vesicle extracellular organelle protein-containing complex IgA immunoglobulin complex immunoglobulin complex IgA immunoglobulin complex, circulating cellular anatomical structure secretory IgA immunoglobulin complex extracellular region extracellular protein-containing complex polymeric IgA immunoglobulin complex immunoglobulin complex, circulating extracellular exosome membrane-bounded organelle extracellular vesicle extracellular organelle organelle vesicle extracellular membrane-bounded organelle cell periphery plasma membrane membrane dimeric IgA immunoglobulin complex secretory dimeric IgA immunoglobulin complex blood microparticle monomeric IgA immunoglobulin complex
E [auth J]	Secretory component	polymeric immunoglobulin binding protein-containing complex binding binding immunoglobulin binding molecular transducer activity immunoglobulin receptor activity transmembrane signaling receptor activity signaling receptor activity polymeric immunoglobulin receptor activity immune receptor activity	cellular response to stimulus immune response-regulating cell surface receptor signaling pathway regulation of biological process regulation of cellular process response to stimulus cell surface receptor signaling pathway signaling immune response biological regulation cell communication Fc receptor signaling pathway immune response-regulating signaling pathway regulation of response to stimulus immune system process cellular response to stimulus immune response-regulating cell surface receptor signaling pathway regulation of biological process regulation of cellular process response to stimulus cell surface receptor signaling pathway signaling immune response biological regulation cell communication Fc receptor signaling pathway immune response-regulating signaling pathway regulation of response to stimulus immune system process regulation of immune response cellular process regulation of immune system process signal transduction cell surface receptor protein tyrosine kinase signaling pathway ERBB signaling pathway epidermal growth factor receptor signaling pathway enzyme-linked receptor protein signaling pathway localization cellular localization receptor clustering macromolecule localization intracellular protein localization localization within membrane protein localization to membrane multicellular organismal process transport establishment of localization immunoglobulin transcytosis in epithelial cells vesicle-mediated transport immunoglobulin transcytosis in epithelial cells mediated by polymeric immunoglobulin receptor transcytosis mucosal immune response organ or tissue specific immune response system process nervous system process detection of chemical stimulus involved in sensory perception of bitter taste detection of chemical stimulus involved in sensory perception of taste detection of stimulus sensory perception of chemical stimulus sensory perception sensory perception of taste response to chemical detection of chemical stimulus sensory perception of bitter taste detection of stimulus involved in sensory perception detection of chemical stimulus involved in sensory perception	protein-containing complex signaling receptor complex IgA immunoglobulin complex, circulating cellular anatomical structure secretory IgA immunoglobulin complex extracellular region IgA immunoglobulin complex extracellular protein-containing complex polymeric IgA immunoglobulin complex immunoglobulin complex, circulating immunoglobulin complex extracellular exosome membrane-bounded organelle extracellular vesicle protein-containing complex signaling receptor complex IgA immunoglobulin complex, circulating cellular anatomical structure secretory IgA immunoglobulin complex extracellular region IgA immunoglobulin complex extracellular protein-containing complex polymeric IgA immunoglobulin complex immunoglobulin complex, circulating immunoglobulin complex extracellular exosome membrane-bounded organelle extracellular vesicle extracellular organelle organelle vesicle extracellular membrane-bounded organelle intracellular anatomical structure intracellular vesicle lytic vacuole endomembrane system intracellular organelle bounding membrane of organelle vesicle membrane cytoplasmic vesicle lysosome vacuolar membrane membrane azurophil granule vacuole intracellular membrane-bounded organelle lytic vacuole membrane cytoplasmic vesicle membrane lysosomal membrane secretory granule primary lysosome secretory vesicle azurophil granule membrane cytoplasm organelle membrane secretory granule membrane cell periphery plasma membrane
F [auth L], G [auth M], H [auth N], I [auth O]	Immunoglobulin light chain	-	-	-
J [auth S]	Secretory component	polymeric immunoglobulin binding protein-containing complex binding binding immunoglobulin binding molecular transducer activity immunoglobulin receptor activity transmembrane signaling receptor activity signaling receptor activity polymeric immunoglobulin receptor activity immune receptor activity	cellular response to stimulus immune response-regulating cell surface receptor signaling pathway regulation of biological process regulation of cellular process response to stimulus cell surface receptor signaling pathway signaling immune response biological regulation cell communication Fc receptor signaling pathway immune response-regulating signaling pathway regulation of response to stimulus immune system process cellular response to stimulus immune response-regulating cell surface receptor signaling pathway regulation of biological process regulation of cellular process response to stimulus cell surface receptor signaling pathway signaling immune response biological regulation cell communication Fc receptor signaling pathway immune response-regulating signaling pathway regulation of response to stimulus immune system process regulation of immune response cellular process regulation of immune system process signal transduction cell surface receptor protein tyrosine kinase signaling pathway ERBB signaling pathway epidermal growth factor receptor signaling pathway enzyme-linked receptor protein signaling pathway localization cellular localization receptor clustering macromolecule localization intracellular protein localization localization within membrane protein localization to membrane multicellular organismal process transport establishment of localization immunoglobulin transcytosis in epithelial cells vesicle-mediated transport immunoglobulin transcytosis in epithelial cells mediated by polymeric immunoglobulin receptor transcytosis mucosal immune response organ or tissue specific immune response system process nervous system process detection of chemical stimulus involved in sensory perception of bitter taste detection of chemical stimulus involved in sensory perception of taste detection of stimulus sensory perception of chemical stimulus sensory perception sensory perception of taste response to chemical detection of chemical stimulus sensory perception of bitter taste detection of stimulus involved in sensory perception detection of chemical stimulus involved in sensory perception	protein-containing complex signaling receptor complex IgA immunoglobulin complex, circulating cellular anatomical structure secretory IgA immunoglobulin complex extracellular region IgA immunoglobulin complex extracellular protein-containing complex polymeric IgA immunoglobulin complex immunoglobulin complex, circulating immunoglobulin complex extracellular exosome membrane-bounded organelle extracellular vesicle protein-containing complex signaling receptor complex IgA immunoglobulin complex, circulating cellular anatomical structure secretory IgA immunoglobulin complex extracellular region IgA immunoglobulin complex extracellular protein-containing complex polymeric IgA immunoglobulin complex immunoglobulin complex, circulating immunoglobulin complex extracellular exosome membrane-bounded organelle extracellular vesicle extracellular organelle organelle vesicle extracellular membrane-bounded organelle intracellular anatomical structure intracellular vesicle lytic vacuole endomembrane system intracellular organelle bounding membrane of organelle vesicle membrane cytoplasmic vesicle lysosome vacuolar membrane membrane azurophil granule vacuole intracellular membrane-bounded organelle lytic vacuole membrane cytoplasmic vesicle membrane lysosomal membrane secretory granule primary lysosome secretory vesicle azurophil granule membrane cytoplasm organelle membrane secretory granule membrane cell periphery plasma membrane

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, B, C, D	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
A, B, C, D	IPR003597	Immunoglobulin C1-set	Domain
A, B, C, D	IPR003006	Immunoglobulin/major histocompatibility complex, conserved site	Conserved Site
A, B, C, D	IPR013151	Immunoglobulin-like beta-sandwich domain	Domain
A, B, C, D	IPR050380	Immune Recognition and Response Modulators	Family
A, B, C, D	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
A, B, C, D	IPR007110	Immunoglobulin-like domain	Domain
E [auth J]	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
E [auth J]	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
E [auth J]	IPR013106	Immunoglobulin V-set domain	Domain
E [auth J]	IPR003599	Immunoglobulin domain subtype	Domain
E [auth J]	IPR007110	Immunoglobulin-like domain	Domain
E [auth J]	IPR050671	CD300 family immune receptors	Family
J [auth S]	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
J [auth S]	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
J [auth S]	IPR013106	Immunoglobulin V-set domain	Domain
J [auth S]	IPR003599	Immunoglobulin domain subtype	Domain
J [auth S]	IPR007110	Immunoglobulin-like domain	Domain
J [auth S]	IPR050671	CD300 family immune receptors	Family

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
A, B, C, D	Pharos: P01877	breast cancer
E [auth J]	Pharos: P01833	B-cell chronic lymphocytic leukemia endometriosis invasive ductal breast carcinoma lung carcinoma nasopharyngeal carcinoma ovarian cancer pancreatic intraductal papillary-mucinous neoplasm with low grade dysplasia breast cancer head and neck cancer lung adenocarcinoma malignant colon neoplasm non-small cell lung carcinoma pancreatic ductal adenocarcinoma transitional cell carcinoma breast carcinoma B-cell chronic lymphocytic leukemia endometriosis invasive ductal breast carcinoma lung carcinoma nasopharyngeal carcinoma ovarian cancer pancreatic intraductal papillary-mucinous neoplasm with low grade dysplasia breast cancer head and neck cancer lung adenocarcinoma malignant colon neoplasm non-small cell lung carcinoma pancreatic ductal adenocarcinoma transitional cell carcinoma breast carcinoma IgA glomerulonephritis lung cancer malignant pancreatic neoplasm osteosarcoma pancreatic intraductal papillary-mucinous neoplasm
J [auth S]	Pharos: P01833	B-cell chronic lymphocytic leukemia endometriosis invasive ductal breast carcinoma lung carcinoma nasopharyngeal carcinoma ovarian cancer pancreatic intraductal papillary-mucinous neoplasm with low grade dysplasia breast cancer head and neck cancer lung adenocarcinoma malignant colon neoplasm non-small cell lung carcinoma pancreatic ductal adenocarcinoma transitional cell carcinoma breast carcinoma B-cell chronic lymphocytic leukemia endometriosis invasive ductal breast carcinoma lung carcinoma nasopharyngeal carcinoma ovarian cancer pancreatic intraductal papillary-mucinous neoplasm with low grade dysplasia breast cancer head and neck cancer lung adenocarcinoma malignant colon neoplasm non-small cell lung carcinoma pancreatic ductal adenocarcinoma transitional cell carcinoma breast carcinoma IgA glomerulonephritis lung cancer malignant pancreatic neoplasm osteosarcoma pancreatic intraductal papillary-mucinous neoplasm

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.