HTR4
Domain
Specificity for G(s) G alpha proteins is determined by the length of transmembrane regions 5 and 6 (TM5 and TM6).
Function
G-protein coupled receptor for 5-hydroxytryptamine (serotonin), a biogenic hormone that functions as a neurotransmitter, a hormone and a mitogen (PubMed:10821780, PubMed:16102731, PubMed:35714614, PubMed:9603189). Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of downstream effectors (PubMed:16102731, PubMed:35714614). HTR4 is coupled to G(s) G alpha proteins and mediates activation of adenylate cyclase activity (PubMed:16102731, PubMed:35714614).
Sequence Similarities
Belongs to the G-protein coupled receptor 1 family.
Tissue Specificity
Isoform 5-HT4(A)
Expressed in ileum, brain, and atrium, but not in the ventricle.
Isoform 5-HT4(E)
Mainly expressed in atria and cardiac ventricle.
Isoform 5-HT4(I)
Expressed in all cardiovascular tissues analyzed.
Cellular localization
- Cell membrane
- Multi-pass membrane protein
- Endosome membrane
- Multi-pass membrane protein
- Interaction with SNX27 mediates recruitment to early endosomes, while interaction with NHERF1 and EZR might target the protein to specialized subcellular regions, such as microvilli.
Alternative names
5-hydroxytryptamine receptor 4, 5-HT-4, 5-HT4, Serotonin receptor 4, HTR4