ATP binding domain 4 Discussions
Based on SCOP hierarchy (Superfamily HMM library and genome assignments server)it was found that all three domain: Archaea, Bacteria and Eukaryote belong to superfamily Adenine nucleotide alpha hydrolases-like (AANH-like). The family members in this superfamily include PP-ATPase, Alpha-ANH-like and Arginosuccinate synthase. Based on the phylogeny of ATP binding domain 4 or ATP pyrophosphatase, clan bacteria is missing suggesting that bacteria do not have ATP pyrophosphatase but it may use other type of protein or enzymes in the superfamily to hydrolyse ATP.
There are several other families of ATP pyrophosphatase which do not contain the PP motifs and it is likely they are not homologous to the family. some enzymes appear to contain other version of PP-loop that despite the predicted structural analogy, do not overlap with the PP-motif described here in any database searches (Bork and Koonin, 1994).
