Seems to be able to hydrolyze ADP, UDP and GDP. Supports mig-17 glycosylation and surface expression, which is required for proper migration of distal tip cells during gonad morphogenesis. a ribonucleoside 5'-diphosphate + H2O = a ribonucleoside 5'-phosphate + H(+) + phosphate Expressed in body wall muscles. In contrast to uda-1, expression is not induced by stress. Belongs to the GDA1/CD39 NTPase family.