Enables alpha-mannosidase activity. Acts upstream of or within learning or memory and mannose metabolic process. Predicted to be located in extracellular space and nucleoplasm. Predicted to be active in lysosome. Is expressed in several structures, including alimentary system; genitourinary system; nervous system; respiratory system; and sensory organ. Used to study alpha-mannosidosis. Human ortholog(s) of this gene implicated in alpha-mannosidosis. Orthologous to human MAN2B1 (mannosidase alpha class 2B member 1). [provided by Alliance of Genome Resources, Apr 2022]