Diadenosine polyphosphates (ApnAs) act as extracellular signaling molecules in a broad variety of tissues. They were shown to be hydrolyzed by surface-located enzymes in an asymmetric manner, generating AMP and Apn-1 from ApnA. The molecular identity of the enzymes responsible remains analyzed the potential ofNPP1, NPP2, and NPP3, the three members of the ecto-nucleotide pyro-phosphatase/phosphodiesterase family, to hydrolyze the diadenosine polyphosphates diadenosine 5¢,5¢¢¢-P 1 ,P 3 -triphosphate (Ap3A),.
