Annotations: 9LD2

Cryo-EM structure of SARS-CoV-2 wide-type S trimer in the early fusion intermediate conformation (E-FIC) complexed with ACE2 and 76E1-Fab (focused refinement of the S2-76E1)

External Resource: Annotation

Domain Annotation: ECOD Classification
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 H]	ClpB_D2-small	e9ld2H1	A: alpha arrays	X: Hypothetical protein YqbG-like	H: Hypothetical protein YqbG-like	T: alpha/beta-Hydrolases	F: ClpB_D2-small	ECOD (v295.2)
A	ClpB_D2-small	e9ld2A1	A: alpha arrays	X: Hypothetical protein YqbG-like	H: Hypothetical protein YqbG-like	T: alpha/beta-Hydrolases	F: ClpB_D2-small	ECOD (v295.2)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
B [auth G], E [auth I], H [auth K]	Heavy Chain	IGHV3	-	spike glycoprotein	SAbDab (2026-10-16)
C [auth H], F [auth J], I [auth L]	Light Chain	IGLV2	Lambda	spike glycoprotein	SAbDab (2026-10-16)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, D [auth B], G [auth C]	PF01601	Coronavirus spike glycoprotein S2 (CoV_S2)	Coronavirus spike glycoprotein S2	-	Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
B [auth G], E [auth I], H [auth K]	heavy chain of 76E1 Fab	-	-	-
C [auth H], F [auth J], I [auth L]	light chain of 76E1 Fab	-	-	-
A, D [auth B], G [auth C]	Spike glycoprotein	molecular function activator activity molecular function regulator activity signaling receptor regulator activity receptor ligand activity signaling receptor activator activity host cell surface binding binding host cell surface receptor binding structural constituent of virion structural molecule activity identical protein binding protein 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 cellular process cellular component organization or biogenesis symbiont-mediated disruption of host anatomical structure biological process involved in interspecies interaction between organisms symbiont-mediated disruption of host tissue disruption of anatomical structure in another organism symbiont entry into host cell symbiont entry into 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 cellular process cellular component organization or biogenesis symbiont-mediated disruption of host anatomical structure biological process involved in interspecies interaction between organisms symbiont-mediated disruption of host tissue disruption of anatomical structure in another organism symbiont entry into host cell symbiont entry into host viral life cycle biological process involved in interaction with host biological process involved in symbiotic interaction virion attachment to host cell receptor-mediated virion attachment to host cell adhesion of symbiont to host cell adhesion of symbiont to host fusion of virus membrane with host plasma membrane endocytosis involved in viral entry into host cell symbiont-mediated perturbation of host defense response symbiont-mediated perturbation of host process symbiont-mediated-mediated suppression of host tetherin activity modulation of process of another organism regulation of biological process positive regulation of viral life cycle positive regulation of viral process biological regulation positive regulation of biological process modulation by symbiont of entry into host regulation of viral entry into host cell regulation of viral life cycle regulation of viral process positive regulation of viral entry into host cell positive regulation by symbiont of entry into host regulation of biological process involved in symbiotic interaction symbiont-mediated suppression of host immune response symbiont-mediated suppression of host innate immune response symbiont-mediated perturbation of host immune response symbiont-mediated perturbation of host innate immune response entry receptor-mediated virion attachment to host cell	host cellular component host extracellular region cellular anatomical structure other organism part membrane cell periphery plasma membrane host intracellular membrane-bounded organelle host intracellular part host cell membrane host cell cytoplasm part host intracellular organelle host cell endoplasmic reticulum-Golgi intermediate compartment membrane host cell endoplasmic reticulum-Golgi intermediate compartment host cellular component host extracellular region cellular anatomical structure other organism part membrane cell periphery plasma membrane host intracellular membrane-bounded organelle host intracellular part host cell membrane host cell cytoplasm part host intracellular organelle host cell endoplasmic reticulum-Golgi intermediate compartment membrane host cell endoplasmic reticulum-Golgi intermediate compartment host cell cytoplasm host cell part host intracellular region host cell plasma membrane virion component virion membrane viral membrane viral envelope host cell surface

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, D [auth B], G [auth C]	IPR044873	Spike glycoprotein S2, coronavirus, heptad repeat 1	Domain
A, D [auth B], G [auth C]	IPR044366	Spike (S) protein S1 subunit, receptor-binding domain, SARS-CoV-2	Domain
A, D [auth B], G [auth C]	IPR018548	Spike (S) protein S1 subunit, receptor-binding domain, betacoronavirus	Domain
A, D [auth B], G [auth C]	IPR044341	Spike (S) protein S1 subunit, N-terminal domain, SARS-CoV-like	Domain
A, D [auth B], G [auth C]	IPR032500	Spike glycoprotein S1, N-terminal domain, betacoronavirus-like	Domain
A, D [auth B], G [auth C]	IPR042578	Spike glycoprotein, betacoronavirus	Family
A, D [auth B], G [auth C]	IPR036326	Spike S1 subunit, receptor binding domain superfamily, betacoronavirus	Homologous Superfamily
A, D [auth B], G [auth C]	IPR043002	Spike glycoprotein, N-terminal domain superfamily	Homologous Superfamily
A, D [auth B], G [auth C]	IPR044874	Spike glycoprotein S2, coronavirus, heptad repeat 2	Domain
A, D [auth B], G [auth C]	IPR043473	Spike glycoprotein S2 superfamily, coronavirus	Homologous Superfamily
A, D [auth B], G [auth C]	IPR043607	Coronavirus spike glycoprotein S1, C-terminal	Domain
A, D [auth B], G [auth C]	IPR002552	Spike glycoprotein S2, coronavirus	Domain