Acetylcholine-gated chloride channel subunit. Currents in channels are triggered in response to acetylcholine. Channel properties may be modulated by the formation of homomeric and heteromeric channels. Homopentamer (in vitro). May interact with either acc-3 or acc-4; the interactions do not result in significant heteropentameric ion channel activity. Expressed in RIA, RIG, PHA and AIZ glutamatergic neurons, URX and RIH cholinergic neurons, and in male-specific MCM neurons. Grossly normal movement. Belongs to the ligand-gated ion channel (TC 1.A.9) family.