title: Differential enzymatic characteristics and tissue-specific expression of human TPST-1 and TPST-2.
abstract: Protein tyrosine sulfation is emerging as a widespread post-translational modification in multicellular eukaryotes. The responsible enzyme, named tyrosylprotein sulfotransferase (TPST), catalyzes the sulfate transfer from 3'-phosphoadenosine 5'-phosphosulfate to tyrosine residues of proteins. Two distinct TPSTs, designated TPST-1 and TPST-2, had previously been identified. In the present study, we cloned human TPST-1 and TPST-2 expressed and characterized the recombinant enzymes using peptide substrates. These enzymes displayed distinct acidic pH optima and stimulatory effects of Mn(2+). Additionally, the activity of TPST-2, but not TPST-1, was stimulated in the presence of Mg(2+). Compared with TPST-2, TPST-1 displayed considerably lower K(m) and V(max) for the majority of the tested peptide substrates, implying their differential substrate specificity. Quantitative real-time PCR analysis showed that although the two TPSTs were co-expressed in all 20 human tissues examined, the levels of expression of TPST-1 and TPST-2 varied significantly among different tissues. These latter findings may imply distinct physiological functions of TPST-1 and TPST-2.
authors.affiliation: Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192.
authors.forename: Emi
authors.initials: E
authors.lastname: Mishiro
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sakakibara
authors.forename: Ming-Cheh
authors.initials: MC
authors.lastname: Liu
authors.forename: Masahito
authors.initials: M
authors.lastname: Suiko
mesh_terms: D000595:Amino Acid Sequence; D001921:Brain / Q000201:enzymology; D002413:Cations, Divalent / Q000494:pharmacology; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics*; D009206:Myocardium / Q000201:enzymology; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity; D015238:Sulfotransferases / Q000235:genetics*; D013737:Testis / Q000201:enzymology; D013950:Thymus Gland / Q000201:enzymology; D014599:Uterus / Q000201:enzymology
chemical_list: D002413:Cations, Divalent; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C084882:P-selectin ligand protein; D011994:Recombinant Proteins; D015238:Sulfotransferases; C114740:TPST2 protein, human; C039079:protein-tyrosine sulfotransferase