Members of this protein family contain a domain duplication. The characterized member from Acinetobacter johnsonii is polyphosphate:AMP phosphotransferase (PAP), which can transfer the terminal phosphate from poly(P) to AMP, yielding ADP. In the opposite direction, this enzyme can synthesize poly(P). Each domain of this protein family is homologous to polyphosphate kinase, an enzyme that can run in the forward direction to extend a polyphosphate chain with a new terminal phosphate from ATP, or in reverse to make ATP (or GTP) from ADP (or GDP). [Central intermediary metabolism, Phosphorus compounds]
Jiyao W et al.(2023). "The conserved domain database in 2023.",