PAP-phosphatase_like domains. PAP-phosphatase is a member of the inositol monophosphatase family, and catalyses the hydrolysis of 3'-phosphoadenosine-5'-phosphate (PAP) to AMP. In Saccharomyces cerevisiae, HAL2 (MET22) is involved in methionine biosynthesis and provides increased salt tolerance when over-expressed. Bacterial members of this domain family may differ in their substrate specificity and dephosphorylate different targets, as the substrate binding site does not appear to be conserved in that sub-set.