Probable component of a ligand-gated anion channel. Negatively regulates synaptic transmission and synaptic vesicle release in response to acetylcholine in cholinergic motor neurons. Role in synaptic vesicle release kinetics may be in association with the ligand-gated ion channel protein acc-4. Expressed in the nervous system, with high expression in cholinergic motor neurons and weak expression in GABAergic motor neurons. Expressed in the dorsal nerve cord of L1 larva and on the dorsal side only of L4 larva and adults. Viable, with normal growth, reproduction and locomotion. Increased sensitivity to the acetylcholine esterase inhibitor aldicarb, but normal sensitivity to levamisole, an agonist for postsynaptic acetylcholine receptors on muscles. In response to induced acetylcholine release, the amplitude and rise phase of excitatory postsynaptic currents (eEPSCs) during synaptic transmission is as wild-type, but there is prolonged and slow decay of eEPSCs during the late phase of synaptic transmission, which results in increased release of synaptic vesicles in cholinergic motor neurons. Belongs to the ligand-gated ion channel (TC 1.A.9) family.