Enables alpha-glucosidase activity. Involved in glycogen catabolic process. Acts upstream of or within cholinergic synaptic transmission and neuromuscular synaptic transmission. Predicted to be located in lysosomal membrane. Is expressed in several structures, including eye; heart; liver; muscle; and pleuroperitoneal region. Used to study glycogen storage disease II. Human ortholog(s) of this gene implicated in glycogen storage disease II. Orthologous to human GAA (alpha glucosidase).