5-hydroxytryptamine receptor 3 subunit B (HTR3B)

The 5-hydroxytryptamine receptor 3 subunit B (HTR3B) is a critical component of the 5-HT3 receptor, which is the only ligand-gated ion channel within the serotonin receptor family (UniProt: O95264). Unlike the 5-HT3A subunit, HTR3B cannot form functional homomeric receptors; instead, it heteromerizes with 5-HT3A to form 5-HT3AB complexes, which exhibit significantly higher single-channel conductance and distinct pharmacological properties compared to homomeric 5-HT3A receptors (PubMed: 10359340). These receptors are primarily located in the central and peripheral nervous systems, particularly in the area postrema and the gastrointestinal tract, where they mediate rapid excitatory neurotransmission (NCBI Gene: 3360). Clinically, the 5-HT3B subunit is a major therapeutic target for managing chemotherapy-induced nausea and vomiting (CINV) and irritable bowel syndrome (IBS). Drugs such as ondansetron and palonosetron act as competitive antagonists at the 5-HT3AB complex to block serotonin-induced depolarization of vagal afferents (StatPearls: NBK544242). Genetic variations in the HTR3B gene, such as the rs1176744 polymorphism, have been identified as significant biomarkers that influence the efficacy of antiemetic treatments and individual susceptibility to nausea (PubMed: 21814193). Safety concerns associated with targeting this receptor include dose-dependent QT interval prolongation and gastrointestinal side effects like constipation (FDA: Ondansetron Label).

Other names

Serotonin receptor 3 subunit B5-HT3B5-HT3-BHTR3B5-hydroxytryptamine receptor 3B

Competitive antagonism of the 5-HT3 receptor complex, specifically the heteromeric 5-HT3A/B channel, to prevent serotonin-induced cation influx and neuronal depolarization (StatPearls: NBK544242).