Cleaves a beta-phosphate from the diphosphate groups in PP-InsP5 (diphosphoinositol pentakisphosphate), suggesting that it may play a role in signal transduction. Also able to catalyze the hydrolysis of dinucleoside oligophosphates, with Ap6A and Ap5A being the preferred substrates. The major reaction products are ADP and p4a from Ap6A and ADP and ATP from Ap5A. Also able to hydrolyze 5-phosphoribose 1-diphosphate. diphospho-myo-inositol polyphosphate + H2O = myo-inositol polyphosphate + phosphate. H2O + P(1),P(6)-bis(5'-adenosyl) hexaphosphate = adenosine 5'-pentaphosphate + AMP + 2 H(+) H2O + P(1),P(5)-bis(5'-adenosyl) pentaphosphate = adenosine 5'-tetraphosphate + AMP + 2 H(+) Binds 3 Mg(2+) or Mn(2+) ions per subunit. Mn(2+) may be the true cofactor in vivo. Optimum pH is 8.5. Mainly expressed in testis and, at lower level in brain. According to PubMed:12121577, it is also expressed in pancreas and weakly expressed in thymus, prostate, ovary, lung, small intestine and heart. Belongs to the Nudix hydrolase family. DIPP subfamily.