Enables acetylcholine receptor binding activity. Acts upstream of or within positive regulation of protein localization to plasma membrane and skeletal muscle acetylcholine-gated channel clustering. Located in cell surface and endoplasmic reticulum-Golgi intermediate compartment. Is expressed in several structures, including alimentary system; brain; cardiovascular system; genitourinary system; and immune system. Orthologous to human RER1 (retention in endoplasmic reticulum sorting receptor 1). [provided by Alliance of Genome Resources, Apr 2022]