Tyrosylprotein Sulfotransferase 2/TPST2: ProductsTyrosine O-sulfation is a posttranslational modification found in all multicellular organisms. This reaction is mediated by tyrosylprotein sulfotransferase (TPST), a Golgi enzyme that transfers sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to tyrosine residues contained in polypeptides with acidic motifs to form a tyrosine O-sulfate ester. More than 60 proteins have been identified to be tyrosine sulfated. The function of this modification have been identified in some cases. For example, sulfation of tyrosine residues in the leukocyte adhesion molecule P-selectin glycoprotein ligand 1 (PSGL-1) is required for binding to P-selectin on activated endothelium, and tyrosine sulfation of chemokine receptors CCR5 and CXCR4 has been reported to facilitate HIV-1 entry of target cells. Two TPSTs are found in the human genome. Compared to TPST1, TPST2 has similar tissue distribution and overlapping substrate specificity. In contrast to Tpst1-/- males with normal fertility in mice, Tpst2-/- males are infertile due to severe defects in sperm motility. The enzymatic activity was assayed using an SDS-PAGE based method.