Uses inorganic polyphosphate (polyP) as a donor to convert NDP to NTP. PolyP hydrolysis is slightly faster with UDP, but it can also use ADP, GDP and CDP. [phosphate](n) + ATP = [phosphate](n+1) + ADP [phosphate](n) + CTP = [phosphate](n+1) + CDP [phosphate](n) + GTP = [phosphate](n+1) + GDP [phosphate](n) + UTP = [phosphate](n+1) + UDP Also accepts various divalent metal ions. kcat is 294 min(-1) with UDP as substrate. Optimum pH is 8. Belongs to the polyphosphate kinase 2 (PPK2) family. Class I subfamily.