This is one of the several different receptors for 5-hydroxytryptamine (serotonin), a biogenic hormone that functions as a neurotransmitter, a hormone, and a mitogen. This receptor is a ligand-gated ion channel, which when activated causes fast, depolarizing responses. It is a cation-specific, but otherwise relatively nonselective, ion channel. Forms a pentaheteromeric complex with HTR3A. Not functional as a homomeric complex. Presumably retained within the endoplasmic reticulum unless complexed with HTR3A. Expressed in adult colon and intestine. Belongs to the ligand-gated ion channel (TC 1.A.9) family. 5-hydroxytryptamine receptor (TC 1.A.9.2) subfamily. HTR3E sub-subfamily.