Tyrosine sulfation of proteins is an important post-translational modification shown to play a role in many membrane-associated or extracellular processes such as virus entry, blood clotting, antibody-mediated immune response, inflammation and egg fecundation. The sole two human enzymes that transfer sulfate moieties from 3'-phospho-adenosine-5'-phospho-sulfate onto tyrosine residues, TPST1 and TPST2, are anchored to the membranes of the trans-Golgi compartment with the catalytic domain oriented to the lumen. In contrast to the relatively well studied organization of medial Golgi enzymes, the organization of trans-Golgi transferases remains elusive. Although tyrosylprotein sulfotransferases are known to exist as homodimers in the Golgi membranes, this organization level may represent only a small piece of a puzzle that is linked to the entire picture. Here we report the formation of TPST1/TPST2 heterodimers and a novel interaction between either TPST1 or TPST2 and the α-2,6-sialyltransferase, indicating a higher organization level of tyrosylprotein sulfotransferases that may serve for substrate selectivity and/or effective organization of multiple post-translational modification of proteins.
Hartmann-Fatu, C., Trusch, F., Moll, C. N., Michin, I., Hassinen, A., Kellokumpu, S., & Bayer, P. (2015). Heterodimers of Tyrosylprotein Sulfotransferases Suggest Existence of a Higher Organization Level of Transferases in the Membrane of the trans-Golgi Apparatus. Journal of Molecular Biology, 427(6 Part B), 1404-1412. https://doi.org/10.1016/j.jmb.2015.01.021