sentences:  In this mechanism, both PAPS and the target tyrosine bind to the same active site in the enzyme and are orientated in a way such that a glutamic acid residue acts as a catalytic base on the tyrosine hydroxyl group, an arginine residue acts as a catalytic acid, and serine and lysine residues are used to stabilize the SN2-like intermediate.The deprotonated hydroxyl would attack the sulfonate group, then displace the phosphate group and PAP would be released, along with the sulfotyrosine residue.Human genes that encode protein-tyrosine sulfotransferase enzymes include