Annotations: 4PIR

X-ray structure of the mouse serotonin 5-HT3 receptor

External Resource: Annotation

Domain Annotation: ECOD Classification
Domain Annotation: CATH
SAbDab Antibody Annotation
Protein Family Annotation
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification
Membrane Protein Annotation: OPM
Membrane Protein Annotation: PDBTM
Membrane Protein Annotation: MemProtMD
Membrane Protein Annotation: mpstruc

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
J		e4pirJ1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
I		e4pirI1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
H		e4pirH1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
G		e4pirG1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
F		e4pirF1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
E		e4pirE1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
D		e4pirD1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
C		e4pirC1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
B		e4pirB1	A: beta barrels	X: avirulence protein AvrPiz-t homologs	H: avirulence protein AvrPiz-t homologs	T: avirulence protein AvrPiz-t homologs	F:	ECOD (v294.2)
A	Rieske	e4pirA1	A: beta barrels	X: HAD domain-like	H: Hemagglutinin HA2 chain	T: Hemagglutinin HA2 chain	F: Rieske	ECOD (v294.2)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
J	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
I	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
H	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
G	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
F	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
E	2.70.170.10	Mainly Beta	Distorted Sandwich	Acetylcholine Binding Protein	Chain: A,	CATH (4.3.0)
D	2.70.170.10	Mainly Beta	Distorted Sandwich	Acetylcholine Binding Protein	Chain: A,	CATH (4.3.0)
C	2.70.170.10	Mainly Beta	Distorted Sandwich	Acetylcholine Binding Protein	Chain: A,	CATH (4.3.0)
B	2.70.170.10	Mainly Beta	Distorted Sandwich	Acetylcholine Binding Protein	Chain: A,	CATH (4.3.0)
A	2.70.170.10	Mainly Beta	Distorted Sandwich	Acetylcholine Binding Protein	Chain: A,	CATH (4.3.0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
F, G, H, I, J	Heavy Chain	IGHV1	-	5-hydroxytryptamine receptor 3a	SAbDab (2026-05-08)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, B, C, D, E	PF02932	Neurotransmitter-gated ion-channel transmembrane region (Neur_chan_memb)	Neurotransmitter-gated ion-channel transmembrane region	-	Family
A, B, C, D, E	PF02931	Neurotransmitter-gated ion-channel ligand binding domain (Neur_chan_LBD)	Neurotransmitter-gated ion-channel ligand binding domain	-	Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
F, G, H, I, J	VHH15	-	-	-
A, B, C, D, E	5-hydroxytryptamine receptor 3A	cation binding binding ion binding serotonin binding amine binding heterocyclic compound binding small molecule binding ligand-gated channel activity ligand-gated monoatomic ion channel activity passive transmembrane transporter activity gated channel activity ligand-gated monoatomic ion channel activity involved in regulation of presynaptic membrane potential monoatomic ion channel activity channel activity cation binding binding ion binding serotonin binding amine binding heterocyclic compound binding small molecule binding ligand-gated channel activity ligand-gated monoatomic ion channel activity passive transmembrane transporter activity gated channel activity ligand-gated monoatomic ion channel activity involved in regulation of presynaptic membrane potential monoatomic ion channel activity channel activity monoatomic ion transmembrane transporter activity transporter activity transmembrane transporter activity excitatory extracellular ligand-gated monoatomic ion channel activity extracellular ligand-gated monoatomic ion channel activity transmitter-gated monoatomic ion channel activity monoatomic cation transmembrane transporter activity molecular transducer activity serotonin-gated monoatomic cation channel activity signaling receptor activity neurotransmitter receptor activity monoatomic cation channel activity serotonin receptor activity transmembrane signaling receptor activity transmitter-gated channel activity ligand-gated monoatomic cation channel activity transmitter-gated monoatomic ion channel activity involved in regulation of postsynaptic membrane potential identical protein binding protein binding	transmembrane transport localization transport monoatomic ion transmembrane transport monoatomic ion transport cellular process establishment of localization cellular response to nitrogen compound cellular response to stimulus response to dopamine regulation of cellular process ligand-gated ion channel signaling pathway response to stimulus signaling transmembrane transport localization transport monoatomic ion transmembrane transport monoatomic ion transport cellular process establishment of localization cellular response to nitrogen compound cellular response to stimulus response to dopamine regulation of cellular process ligand-gated ion channel signaling pathway response to stimulus signaling cellular response to dopamine response to monoamine cell communication response to catecholamine serotonin-gated cation-selective signaling pathway cellular response to catecholamine stimulus signal transduction regulation of biological process serotonin receptor signaling pathway biological regulation response to oxygen-containing compound response to nitrogen compound cellular response to oxygen-containing compound cellular response to chemical stimulus cellular response to monoamine stimulus response to chemical regulation of biological quality regulation of membrane potential trans-synaptic signaling synaptic signaling anterograde trans-synaptic signaling cell-cell signaling chemical synaptic transmission	cell periphery postsynapse cellular anatomical structure postsynaptic membrane synapse cell junction membrane plasma membrane plasma membrane region synaptic membrane presynapse presynaptic membrane cell division site cleavage furrow cell periphery postsynapse cellular anatomical structure postsynaptic membrane synapse cell junction membrane plasma membrane plasma membrane region synaptic membrane presynapse presynaptic membrane cell division site cleavage furrow glutamatergic synapse cell projection neuron projection plasma membrane bounded cell projection protein-containing complex transmembrane transporter complex membrane protein complex transporter complex somatodendritic compartment cell body neuronal cell body axon serotonin-activated cation-selective channel complex plasma membrane protein complex cation channel complex neurotransmitter receptor complex plasma membrane signaling receptor complex signaling receptor complex serotonin receptor complex monoatomic ion channel complex

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, B, C, D, E	IPR006202	Neurotransmitter-gated ion-channel ligand-binding domain	Domain
A, B, C, D, E	IPR036719	Neurotransmitter-gated ion-channel transmembrane domain superfamily	Homologous Superfamily
A, B, C, D, E	IPR049944	5-hydroxytryptamine 3 receptor, transmembrane domain	Domain
A, B, C, D, E	IPR006029	Neurotransmitter-gated ion-channel transmembrane domain	Domain
A, B, C, D, E	IPR036734	Neurotransmitter-gated ion-channel ligand-binding domain superfamily	Homologous Superfamily
A, B, C, D, E	IPR018000	Neurotransmitter-gated ion-channel, conserved site	Conserved Site
A, B, C, D, E	IPR038050	Neuronal acetylcholine receptor	Homologous Superfamily
A, B, C, D, E	IPR008133	5-hydroxytryptamine 3 receptor, A subunit	Family
A, B, C, D, E	IPR008132	5-hydroxytryptamine 3 receptor	Family
A, B, C, D, E	IPR006201	Neurotransmitter-gated ion-channel	Family

Membrane Protein Annotation: OPM OPM Database Homepage

Chains	External Link	Type	Class	Superfamily	Family
A, B, C, D, E	OPM	Transmembrane	Alpha-helical polytopic	Pentameric ligand-gated ion channels	Ligand-gated ion channel of neurotransmitter receptors

Membrane Protein Annotation: PDBTM PDBTM Database Homepage

Chains	External Link	Comment
A, B, C, D, E	PDBTM	Annotated as membrane protein by PDBTM

Membrane Protein Annotation: MemProtMD MemProtMD Database Homepage

Chains	External Link	Comment
A, B, C, D, E	MemProtMD	Annotated as membrane protein by MemProtMD

Membrane Protein Annotation: mpstruc mpstruc Database Homepage

Chains	Resource Link	Group	Subgroup	Protein
A, B, C, D, E	mpstruc	TRANSMEMBRANE PROTEINS: ALPHA-HELICAL	Cys-Loop Receptor Family	Serotonin 5-HT_3A receptor

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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.

4PIR | pdb_00004pir