Tyrosylprotein Sulfotransferase 2 catalyzes the O-sulfation of tyrosine residues within acidic regions of proteins. A 304-residue segment in the luminal domain of TPST2 shows 75% amino acid identity to the corresponding segment of TPST1, including conservation of the residues implicated in the binding of 3-prime-phosphoadenosine 5-prime-phosphosulfate (PAPS). Expression of the TPST2 cDNA in CHO cells resulted in an approximately 13-fold increase in both TPST protein, as determined by MSC labeling, and TPST activity. A predicted 359-residue type II transmembrane protein in Caenorhabditis elegans with 45% amino acid identity to TPST2 in a 257-residue segment of the luminal domain pointed to the evolutionary conservation of the TPST protein family.