Broad specificity cytosolic 5'-nucleotidase that catalyzes the dephosphorylation of 6-hydroxypurine nucleoside 5'-monophosphates (PubMed:6260203). 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 (By similarity). Has the highest activities for IMP and GMP followed by dIMP, dGMP and XMP (PubMed:6260203). Could also catalyze the transfer of phosphates from pyrimidine monophosphates but with lower efficiency (By similarity). Through these activities regulates the purine nucleoside/nucleotide pools within the cell (PubMed:6260203). 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 dIMP + H2O = 2'-deoxyinosine + phosphate dGMP + H2O = 2'-deoxyguanosine + 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 (PubMed:6260203). Binding of an allosteric activator is a prerequisiste to magnesium and substrate binding (By similarity). Inhibited by inorganic phosphate (PubMed:6260203). Optimum pH is 6.5. Homotetramer. Belongs to the 5'(3')-deoxyribonucleotidase family.