The protein encoded this gene belongs to the ligand-gated ion channel receptor superfamily. This gene encodes subunit D of the type 3 receptor for 5-hydroxytryptamine (serotonin), a biogenic hormone that functions as a neurotransmitter, a mitogen and a hormone. This hormone has been linked to neuropsychiatric disorders, including anxiety, depression, and migraine. Serotonin receptors causes fast and depolarizing responses in neurons following activation. The genes encoding subunits C, D and E of this type 3 receptor form a cluster on chromosome 3. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.HTR3D (5-Hydroxytryptamine Receptor 3D) is a Protein Coding gene. Among its related pathways are Serotonergic synapse and Transport of glucose and other sugars, bile salts and organic acids, metal ions and amine compounds. GO annotations related to this gene include extracellular ligand-gated ion channel activity and G-protein coupled serotonin receptor activity. An important paralog of this gene is HTR3E.