Annotations: 9N7Q

H1 hemagglutinin (A/Michigan/45/2015) in complex with anchor-targeting Fab ST15

External Resource: Annotation

SAbDab Antibody Annotation
Protein Family Annotation
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification
Pharos: Disease Associations

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
B [auth L], F [auth G], J [auth F]	Light Chain	IGKV3	Kappa	unknown \| h1 ha2	SAbDab (2026-09-25)
A [auth H], E, I [auth D]	Heavy Chain	IGHV3	-	unknown \| h1 ha2	SAbDab (2026-09-25)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A [auth H], E, I [auth D]	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
D [auth a], H [auth b], L [auth c]	H1 HA2	host cell surface binding binding host cell surface receptor binding	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 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 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 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 non-lytic viral release viral budding virion assembly exit from host cell viral budding from plasma membrane viral release from host cell import into cell receptor-mediated endocytosis of virus by host cell transport establishment of localization vesicle-mediated transport localization symbiont entry into host cell clathrin-dependent endocytosis symbiont entry into host clathrin-dependent endocytosis of virus by host cell receptor-mediated endocytosis endocytosis endocytosis involved in viral entry into host cell	cellular anatomical structure membrane virion component virion membrane viral membrane viral envelope host cell plasma membrane host cellular component host cell part host cell membrane other organism part
C [auth A], G [auth B], K [auth C]	H1 HA1	host cell surface binding binding host cell surface receptor binding	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 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 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 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 non-lytic viral release viral budding virion assembly exit from host cell viral budding from plasma membrane viral release from host cell import into cell receptor-mediated endocytosis of virus by host cell transport establishment of localization vesicle-mediated transport localization symbiont entry into host cell clathrin-dependent endocytosis symbiont entry into host clathrin-dependent endocytosis of virus by host cell receptor-mediated endocytosis endocytosis endocytosis involved in viral entry into host cell	cellular anatomical structure membrane virion component virion membrane viral membrane viral envelope host cell plasma membrane host cellular component host cell part host cell membrane other organism part
B [auth L], F [auth G], J [auth F]	ST15 Light Chain Fab	-	-	cell periphery cellular anatomical structure plasma membrane membrane extracellular region
A [auth H], E, I [auth D]	ST15 Heavy Chain Fab	binding antigen binding	adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity response to stimulus immune response immune system process B cell mediated immunity leukocyte mediated immunity immunoglobulin mediated immune response adaptive immune response immune effector process	cellular anatomical structure extracellular region blood microparticle cell periphery plasma membrane membrane extracellular exosome membrane-bounded organelle extracellular vesicle extracellular organelle organelle vesicle extracellular membrane-bounded organelle

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
D [auth a], H [auth b], L [auth c]	IPR001364	Haemagglutinin, influenzavirus A/B	Family
D [auth a], H [auth b], L [auth c]	IPR008980	Viral capsid/haemagglutinin protein	Homologous Superfamily
D [auth a], H [auth b], L [auth c]	IPR000149	Haemagglutinin, influenzavirus A	Family
D [auth a], H [auth b], L [auth c]	IPR013828	Haemagglutinin, HA1 chain, alpha/beta domain superfamily	Homologous Superfamily
C [auth A], G [auth B], K [auth C]	IPR001364	Haemagglutinin, influenzavirus A/B	Family
C [auth A], G [auth B], K [auth C]	IPR008980	Viral capsid/haemagglutinin protein	Homologous Superfamily
C [auth A], G [auth B], K [auth C]	IPR000149	Haemagglutinin, influenzavirus A	Family
C [auth A], G [auth B], K [auth C]	IPR013828	Haemagglutinin, HA1 chain, alpha/beta domain superfamily	Homologous Superfamily
B [auth L], F [auth G], J [auth F]	IPR050150	Immunoglobulin Variable Light Chain	Family
B [auth L], F [auth G], J [auth F]	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
B [auth L], F [auth G], J [auth F]	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
B [auth L], F [auth G], J [auth F]	IPR013106	Immunoglobulin V-set domain	Domain
B [auth L], F [auth G], J [auth F]	IPR003599	Immunoglobulin domain subtype	Domain
B [auth L], F [auth G], J [auth F]	IPR007110	Immunoglobulin-like domain	Domain
A [auth H], E, I [auth D]	IPR050199	Immunoglobulin Heavy Variable	Family
A [auth H], E, I [auth D]	IPR013783	Immunoglobulin-like fold	Homologous Superfamily
A [auth H], E, I [auth D]	IPR036179	Immunoglobulin-like domain superfamily	Homologous Superfamily
A [auth H], E, I [auth D]	IPR013106	Immunoglobulin V-set domain	Domain
A [auth H], E, I [auth D]	IPR007110	Immunoglobulin-like domain	Domain

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
A [auth H], E, I [auth D]	: P01764	B-cell chronic lymphocytic leukemia large cell medulloblastoma malignant colon neoplasm periodontitis ulcerative colitis cystic fibrosis lung adenocarcinoma non-small cell lung carcinoma plasma cell myeloma interstitial cystitis lung cancer osteosarcoma sinusitis