4FAB | pdb_00004fab

THREE-DIMENSIONAL STRUCTURE OF A FLUORESCEIN-FAB COMPLEX CRYSTALLIZED IN 2-METHYL-2,4-PENTANEDIOL

External Resource: Annotation

Domain Annotation: SCOP/SCOPe 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

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

Chains	Domain Info	Class	Fold	Superfamily	Family	Domain	Species	Provenance Source (Version)
B [auth H]	d4fabh1	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	V set domains (antibody variable domain-like)	Immunoglobulin heavy chain variable domain, VH	house mouse (Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
B [auth H]	d4fabh2	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	C1 set domains (antibody constant domain-like)	Immunoglobulin heavy chain gamma constant domain 1, CH1-gamma	house mouse (Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
A [auth L]	d4fabl1	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	V set domains (antibody variable domain-like)	Immunoglobulin light chain kappa variable domain, VL-kappa	house mouse (Mus musculus ) [TaxId: 10090 ],	SCOPe (2.08)
A [auth L]	d4fabl2	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	C1 set domains (antibody constant domain-like)	Immunoglobulin light chain kappa constant domain, CL-kappa	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)
B [auth H]		e4fabH1	A: Cloacin translocation domain	X: Cloacin translocation domain	H: Cloacin translocation domain	T: Copper-bind	F:	ECOD (20:10:01)
A [auth L]		e4fabL1	A: Cloacin translocation domain	X: Cloacin translocation domain	H: Cloacin translocation domain	T: Copper-bind	F:	ECOD (20:10:01)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
B [auth H]	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
A [auth L]	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 [auth H]	4-4-20 mAb	VH-CH1	Mus musculus (house mouse)	IGHV6-702, IGHJ401, IGHG2A01, IGHG2A02	V-DOMAIN VH, C-DOMAIN CH1	IG	FAB-GAMMA-2A_KAPPA	IMGT (202609-0)
A [auth L]	4-4-20 mAb	L-KAPPA	Mus musculus (house mouse)	IGKV1-11001, IGKJ101, IGKJ102, IGKC01, IGKC*02	V-DOMAIN V-KAPPA, C-DOMAIN C-KAPPA	IG	FAB-GAMMA-2A_KAPPA	IMGT (202609-0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
B [auth H]	Heavy Chain	IGHV6	-	FLUORESCIN	SAbDab (2026-03-13)
A [auth L]	Light Chain	IGKV1	Kappa	FLUORESCIN	SAbDab (2026-03-13)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
B [auth H]	PF07654	Immunoglobulin C1-set domain (C1-set)	Immunoglobulin C1-set domain		Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
B [auth H]	IGG2A-KAPPA 4-4-20 FAB (HEAVY CHAIN)	protein-containing complex binding protein binding binding signaling receptor binding immunoglobulin receptor binding Fc-gamma receptor I complex binding antigen binding	regulation of biological process response to stimulus immune response biological regulation positive regulation of biological process positive regulation of response to stimulus positive regulation of immune response regulation of response to stimulus immune system process regulation of immune response regulation of immune system process positive regulation of immune system process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity regulation of biological process response to stimulus immune response biological regulation positive regulation of biological process positive regulation of response to stimulus positive regulation of immune response regulation of response to stimulus immune system process regulation of immune response regulation of immune system process positive regulation of immune system process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity B cell mediated immunity leukocyte mediated immunity immunoglobulin mediated immune response adaptive immune response immune effector process membrane organization import into cell transport establishment of localization vesicle-mediated transport cellular component organization localization phagocytosis, engulfment membrane invagination cellular process phagocytosis cellular component organization or biogenesis endocytosis plasma membrane invagination positive regulation of acute inflammatory response to antigenic stimulus regulation of immune effector process regulation of acute inflammatory response to antigenic stimulus positive regulation of leukocyte mediated immunity inflammatory response to antigenic stimulus positive regulation of hypersensitivity positive regulation of inflammatory response positive regulation of adaptive immune response positive regulation of immunoglobulin mediated immune response hypersensitivity regulation of adaptive immune response response to external stimulus regulation of inflammatory response regulation of B cell mediated immunity regulation of leukocyte mediated immunity positive regulation of defense response regulation of acute inflammatory response inflammatory response positive regulation of type I hypersensitivity regulation of type I hypersensitivity regulation of defense response regulation of response to external stimulus positive regulation of adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains positive regulation of lymphocyte mediated immunity positive regulation of acute inflammatory response positive regulation of B cell mediated immunity type I hypersensitivity positive regulation of response to external stimulus regulation of adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains response to stress regulation of response to stress regulation of immunoglobulin mediated immune response positive regulation of immune effector process acute inflammatory response regulation of hypersensitivity defense response regulation of inflammatory response to antigenic stimulus acute inflammatory response to antigenic stimulus positive regulation of inflammatory response to antigenic stimulus regulation of lymphocyte mediated immunity myeloid leukocyte mediated immunity antibody-dependent cellular cytotoxicity leukocyte mediated cytotoxicity type II hypersensitivity type IIa hypersensitivity cell killing cellular localization endosome to lysosome transport intracellular transport lysosomal transport establishment of localization in cell vacuolar transport humoral immune response complement activation humoral immune response mediated by circulating immunoglobulin complement activation, classical pathway activation of immune response regulation of cellular process regulation of protein metabolic process primary metabolic process regulation of macromolecule metabolic process regulation of primary metabolic process regulation of proteolysis proteolysis metabolic process protein metabolic process macromolecule metabolic process regulation of metabolic process biological process involved in interspecies interaction between organisms response to other organism antibacterial humoral response defense response to symbiont antimicrobial humoral response response to biotic stimulus defense response to bacterium defense response to other organism response to bacterium response to external biotic stimulus regulation of localization positive regulation of cellular component organization regulation of cellular component organization positive regulation of endocytosis positive regulation of cellular process regulation of endocytosis regulation of transport regulation of phagocytosis regulation of vesicle-mediated transport positive regulation of phagocytosis positive regulation of transport regulation of myeloid leukocyte mediated immunity regulation of type IIa hypersensitivity regulation of type II hypersensitivity positive regulation of myeloid leukocyte mediated immunity positive regulation of type IIa hypersensitivity positive regulation of type II hypersensitivity multicellular organismal process regulation of leukocyte activation regulation of cell activation lymphocyte activation leukocyte activation positive regulation of lymphocyte activation positive regulation of cell activation regulation of B cell activation positive regulation of leukocyte activation regulation of multicellular organismal process B cell activation cell activation positive regulation of B cell activation positive regulation of multicellular organismal process regulation of lymphocyte activation antigen processing and presentation endosomal transport vesicle-mediated transport between endosomal compartments early endosome to late endosome transport phagocytosis, recognition cell recognition	cell periphery cellular anatomical structure plasma membrane membrane IgG immunoglobulin complex protein-containing complex immunoglobulin complex membrane-bounded organelle intracellular anatomical structure endosome intracellular vesicle intracellular membrane-bounded organelle endomembrane system intracellular organelle cell periphery cellular anatomical structure plasma membrane membrane IgG immunoglobulin complex protein-containing complex immunoglobulin complex membrane-bounded organelle intracellular anatomical structure endosome intracellular vesicle intracellular membrane-bounded organelle endomembrane system intracellular organelle cytoplasmic vesicle organelle late endosome cytoplasm multivesicular body vesicle extracellular region extracellular space immunoglobulin complex, circulating
A [auth L]	IGG2A-KAPPA 4-4-20 FAB (LIGHT CHAIN)	-	-	-

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
B [auth H]	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
B [auth H]	IPR003597	Immunoglobulin C1-set	Domain
B [auth H]	IPR003006	Immunoglobulin/major histocompatibility complex, conserved site	Conserved Site
B [auth H]	IPR050380	Immune Recognition and Response Modulators	Family
B [auth H]	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
B [auth H]	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.