Tyrosine sulfation

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Tyrosine sulfation is a posttranslational modification where a sulfate group is added to a tyrosine residue of a protein molecule. Secreted proteins and extracellular parts of membrane proteins that pass through the Golgi apparatus may be sulfated. Sulfation was first dicovered by Betteheim in bovine fibrinopeptide B in 1954 and later found be be present in animals and plants but not in prokaryotes or in yeast.

1 Function
2 Mechanism
3 Regulation
4 References

[edit] Function

Sulfation plays role in strengthening protein-protein interactions. Types of human proteins known to undergo tyrosine sulfation include adhesion molecules, G-protein-coupled receptors, coagulation factors, serine protease inhibitors, extracellular matrix proteins, and hormones. Tyrosine O-sulfate is a stable molecule and is excreted in urine in animals. No enzymatic mechanism of tyrosine sulfate desulfation is known to exist.

By knock-out of TPST genes in mice, it may be observed that Tyrosine sulfation has effects on the growth of the mice, such as body weight, fecundity, and postnatal viability.

[edit] Mechanism

Sulfation is catalyzed by tyrosylprotein sulfotransferase (TPST) in Golgi apparatus. The reaction catalyzed by TPST is a transfer of sulfate from the universal sulfate donor 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to the side-chain hydroxyl group of a tyrosine residue. Sulfation sites are have a tyrosine residues exposed on the surface of the protein typically surrounded by acidic residues, a detailed description of the characteristics of the sulfation site is available from PROSITE (PROSITE pattern: PS00003)[1]. Two types of tyrosylprotein sulftotransferases (TPST-1 and TPST2) have been identified.

[edit] Regulation

There is very limited evidence that the TPST genes are subject to transcriptional regulation and tyrosine O-sulfate is very stable and cannot be easily degraded by mammalian sulfatases. Tyrosine O-sulfation is an irreversible process in vivo.