2XRA | pdb_00002xra

crystal structure of the HK20 Fab in complex with a gp41 mimetic 5- Helix

External Resource: Annotation

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: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
C [auth L]	Glyco_trans_1_4	e2xraL1	A: a/b three-layered sandwiches	X: Lipocalins/Streptavidin	H: Zn-dependent exopeptidases	T: Zn-dependent exopeptidases	F: Glyco_trans_1_4	ECOD (v294.1)
B [auth H]	Ribosomal_L1	e2xraH1	A: a/b three-layered sandwiches	X: N-terminal beta-sandwich domain in anthrax protective antigen	H: Macro domain-like	T: Macro domain-like	F: Ribosomal_L1	ECOD (v294.1)
A	Beta-Casp	e2xraA1	A: a/b three-layered sandwiches	X: Alpha-beta plaits	H: Pseudouridine synthase	T: Pseudouridine synthase	F: Beta-Casp	ECOD (v294.1)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
C [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
C [auth L]	Fab HK20 mAb, anti-gp41 [HIV-1]	L-KAPPA	Homo sapiens (human)	IGKV1-3301, IGKV1D-3301, IGKJ501, IGKC01	V-DOMAIN V-KAPPA, C-DOMAIN C-KAPPA	IG	FAB-GAMMA-1_KAPPA	IMGT (202614-0)
B [auth H]	Fab HK20 mAb, anti-gp41 [HIV-1]	VH-CH1	Homo sapiens (human)	IGHV1-6905, IGHJ302, IGHG101, IGHG102, IGHG1*04	V-DOMAIN VH, C-DOMAIN CH1	IG	FAB-GAMMA-1_KAPPA	IMGT (202614-0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
C [auth L]	Light Chain	IGKV1	Kappa	transmembrane protein gp41	SAbDab (2026-04-17)
B [auth H]	Heavy Chain	IGHV1	-	transmembrane protein gp41	SAbDab (2026-04-17)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A	PF00517	Retroviral envelope protein (GP41)	Retroviral envelope protein	-	Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
C [auth L]	HK20, HUMAN MONOCLONAL ANTIBODY LIGHT CHAIN	-	-	-
B [auth H]	HK20, HUMAN MONOCLONAL ANTIBODY HEAVY CHAIN	-	-	-
A	TRANSMEMBRANE PROTEIN GP41	molecular function activator activity molecular function regulator activity signaling receptor regulator activity receptor ligand activity signaling receptor activator activity structural molecule activity	viral process fusion of virus membrane with host endosome membrane membrane fusion involved in viral entry into host cell membrane organization cellular component organization membrane fusion fusion of virus membrane with host plasma membrane cellular process cellular component organization or biogenesis regulation of establishment of T cell polarity regulation of establishment or maintenance of cell polarity multicellular organismal process establishment of lymphocyte polarity regulation of cellular process viral process fusion of virus membrane with host endosome membrane membrane fusion involved in viral entry into host cell membrane organization cellular component organization membrane fusion fusion of virus membrane with host plasma membrane cellular process cellular component organization or biogenesis regulation of establishment of T cell polarity regulation of establishment or maintenance of cell polarity multicellular organismal process establishment of lymphocyte polarity regulation of cellular process regulation of leukocyte activation establishment of T cell polarity positive regulation of biological process regulation of cell activation positive regulation of leukocyte cell-cell adhesion establishment or maintenance of cell polarity lymphocyte activation leukocyte cell-cell adhesion leukocyte activation positive regulation of cell-cell adhesion positive regulation of lymphocyte activation positive regulation of cell activation cell adhesion cell-cell adhesion T cell activation positive regulation of establishment of T cell polarity positive regulation of leukocyte activation regulation of multicellular organismal process regulation of immune system process regulation of cell-cell adhesion positive regulation of immune system process positive regulation of cellular process regulation of biological process positive regulation of T cell activation positive regulation of cell adhesion regulation of cell adhesion cell activation biological regulation regulation of T cell activation establishment of cell polarity regulation of establishment of cell polarity immune system process regulation of leukocyte cell-cell adhesion positive regulation of multicellular organismal process regulation of lymphocyte activation regulation of localization cellular localization regulation of protein localization positive regulation of receptor clustering positive regulation of protein localization to membrane localization within membrane protein localization to membrane localization regulation of cellular localization macromolecule localization receptor clustering positive regulation of protein localization intracellular protein localization regulation of receptor clustering regulation of protein localization to membrane virion attachment to host cell biological process involved in interspecies interaction between organisms adhesion of symbiont to host cell viral life cycle adhesion of symbiont to host biological process involved in interaction with host biological process involved in symbiotic interaction symbiont-mediated perturbation of host defense response response to stimulus response to other organism symbiont-mediated perturbation of host immune response symbiont-mediated response to host defenses response to external stimulus response to biotic stimulus symbiont-mediated perturbation of host process response to host immune response symbiont-mediated evasion of host immune response response to host response to external biotic stimulus modulation of process of another organism symbiont entry into host cell symbiont entry into host plasma membrane raft distribution regulation of cellular component organization positive regulation of cellular component organization plasma membrane raft polarization plasma membrane organization membrane raft organization endomembrane system organization membrane raft distribution plasma membrane raft localization membrane raft polarization regulation of plasma membrane raft polarization membrane raft localization regulation of plasma membrane organization positive regulation of plasma membrane raft polarization import into cell receptor-mediated endocytosis of virus by host cell transport establishment of localization vesicle-mediated transport clathrin-dependent endocytosis clathrin-dependent endocytosis of virus by host cell receptor-mediated endocytosis endocytosis endocytosis involved in viral entry into host cell organelle organization actin cytoskeleton organization actin filament organization actin filament-based process supramolecular fiber organization cytoskeleton organization viral gene expression viral protein processing	cellular anatomical structure membrane virion component virion membrane host intracellular membrane-bounded organelle host cellular component host intracellular part host cell membrane other organism part host cell cytoplasm part host intracellular organelle host cell endosome membrane host cell cytoplasm host cell part cellular anatomical structure membrane virion component virion membrane host intracellular membrane-bounded organelle host cellular component host intracellular part host cell membrane other organism part host cell cytoplasm part host intracellular organelle host cell endosome membrane host cell cytoplasm host cell part host cell endosome host intracellular region viral membrane viral envelope host cell plasma membrane

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A	IPR000777	Human immunodeficiency virus 1, envelope glycoprotein Gp120	Domain
A	IPR036377	Gp120 core superfamily	Homologous Superfamily
A	IPR000328	Retroviral envelope protein GP41-like	Domain
A	IPR037527	Envelope glycoprotein Gp160	Family

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.