Protein Phosphatase Methylesterase 1 (PPME1)

Protein phosphatase methylesterase-1 catalyzes the demethylation of the protein phosphatase-2A catalytic subunit (PPP2CA).The deduced 386-amino acid protein shares 40% and 26% sequence identity with the C. elegans and S. cerevisiae homologs, respectively. Human PPME1 contains a highly charged stretch of amino acids, and all 3 PPME1 homologs contain a consensus sequence for lipases that use an active site serine.PPME1 forms a stable complex with the catalytically inactive mutant subunits but not with the wildtype subunit. Expression of PPME1 in bacteria demonstrated that PPME1 has PPP2CA methylesterase activity that is inhibited by the PPP2CA inhibitor okadaic acid but not by the serine protease inhibitor PMSF.