Annotations: 9FCM

Single-domain antibody binding the SARS-COV2 S2

External Resource: Annotation

Domain Annotation: ECOD Classification
SAbDab Antibody 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	V-set	e9fcmC1	A: alpha arrays	X: Hypothetical protein YqbG-like	H: Hypothetical protein YqbG-like	T: alpha/beta-Hydrolases	F: V-set	ECOD (v295.2)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
A, B, C	Heavy Chain	IGHV1	-	spike protein s2'	SAbDab (2026-08-21)

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
D, E, F	Spike protein S2'	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	cellular anatomical structure membrane host cellular component host extracellular region other organism part 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 cellular anatomical structure membrane host cellular component host extracellular region other organism part 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
A, B, C	Single-domain antibody R3DC23	-	-	-

InterPro: Protein Family Classification InterPro Database Homepage

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

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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.

9FCM | pdb_00009fcm

Single-domain antibody binding the SARS-COV2 S2

External Resource: Annotation

Domain Annotation: ECOD Classification ECOD Database Homepage

SAbDab Antibody Annotation SAbDab Database Homepage

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

InterPro: Protein Family Classification InterPro Database Homepage