May act as a regulatory subunit for mtm-6. In association with phosphatase mtm-6, plays a role in endosome trafficking probably by regulating phosphatidylinositol-3-phosphate levels. Regulates fluid phase endocytosis in coelomocytes. Regulates posterior migration of QL neuroblast descendants and the anterior migration of QR neuroblast descendants and HSN neurons during larval development probably by controlling Wnt ligand secretion through the regulation of sorting receptor mig-14 trafficking. Involved in the formation of correct synapse number in DA9 motor neurons