Predicted to be involved in endocytic recycling; lysosomal transport; and vesicle fusion. Predicted to act upstream of or within protein transport. Part of AP-3 adaptor complex. Is expressed in several structures, including brain; genitourinary system; gut; quadriceps femoris muscle; and trigeminal nerve. Orthologous to human VPS39 (VPS39 subunit of HOPS complex). [provided by Alliance of Genome Resources, Apr 2022]