Catalyzes the hydrolysis of phosphoanhydride bonds of nucleoside tri- and di-phosphates. a ribonucleoside 5'-triphosphate + 2 H2O = a ribonucleoside 5'-phosphate + 2 H(+) + 2 phosphate A number of isoforms are produced. According to EST sequences. Expressed in the initiation zone of lateral root and in the lateral root tip, the adaxial junction of lateral shoots with the stems, and in the abscission zone of flower organs. Not expressed in the rosette leaves. No visible phenotype. Belongs to the GDA1/CD39 NTPase family.