Tyrosine sulfation has been found to be an important part of the inflammatory process, leukocyte movement and cytosis, viral cell entrance, and other cell-cell and protein-protein interactions.

[2][3][4] P-selectin glycoprotein ligand-1 (PSGL-1) has been extensively studied as a substrate for TPST and the importance of sulfation in PSGL-1 and its ability to bind its receptor.

[5] Another substrate for TPST, CC-chemokine Receptor 5 (CCR5), has generated interest because of its role as the target protein for the viral entrance of HIV into cells.

[6] Beyond these two proteins, other notable protein substrates include Cholecystokinin (CCK), Factor V and Factor VIII, gastrin, the leech enzyme hirudin, fibrinogen, Complement component 4, follicle-stimulating hormone receptor (FSHR), and other chemokine and G-protein coupled receptors.

[2][4] It is localized to the Golgi apparatus, specifically in the trans-Golgi region, and acts almost exclusively on secretory and plasma membrane proteins.