Enables G protein-coupled acetylcholine receptor activity. Acts upstream of or within cardiac conduction system development. Predicted to be located in postsynaptic membrane. Predicted to be active in dendrite; plasma membrane; and synapse. Is expressed in eye. Human ortholog(s) of this gene implicated in bladder disease; chronic obstructive pulmonary disease; prune belly syndrome; and pulmonary fibrosis. Orthologous to human CHRM3 (cholinergic receptor muscarinic 3).