Broad specificity cytosolic 5'-nucleotidase that catalyzes the dephosphorylation of 6-hydroxypurine nucleoside 5'-monophosphates. In addition, possesses a phosphotransferase activity by which it can transfer a phosphate from a donor nucleoside monophosphate to an acceptor nucleoside, preferably inosine, deoxyinosine and guanosine. Has the highest activities for IMP and GMP followed by dIMP, dGMP and XMP. Could also catalyze the transfer of phosphates from pyrimidine monophosphates but with lower efficiency. Through these activities regulates the purine nucleoside/nucleotide pools within the cell. a ribonucleoside 5'-phosphate + H2O = a ribonucleoside + phosphate a 2'-deoxyribonucleoside + a ribonucleoside 5'-phosphate = a 2'-deoxyribonucleoside 5'-phosphate + a ribonucleoside H2O + IMP = inosine + phosphate GMP + H2O = guanosine + phosphate dGMP + H2O = 2'-deoxyguanosine + phosphate dIMP + H2O = 2'-deoxyinosine + phosphate H2O + XMP = phosphate + xanthosine GMP + inosine = guanosine + IMP dGMP + inosine = 2'-deoxyguanosine + IMP dIMP + inosine = 2'-deoxyinosine + IMP inosine + UMP = IMP + uridine CMP + inosine = cytidine + IMP AMP + inosine = adenosine + IMP Binds 1 Mg(2+) ion per subunit. Allosterically activated by various compounds including ATP, 2,3-BPG/2,3-Bisphosphoglyceric acid and Ap4A/P1,P4-bis(5'-adenosyl) tetraphosphate. Binding of an allosteric activator is a prerequisiste to magnesium and substrate binding. Inhibited by inorganic phosphate. Homotetramer. Belongs to the 5'(3')-deoxyribonucleotidase family.