Variant surface glycoprotein VSG

The first complete structural characterization of a GPI, achieved by Ferguson and coworkers in 1988, was of the T. brucei variant surface glycoprotein (VSG) anchor [9]. This study was assisted by the fact that the African trypanosome system exhibits abundant VSG (ca. 10 copies per cell) [10], which also facilitated the development of the first cell-free... 

The GPIs started being recognized a unique tool for membrane anchoring after first observations that bacterial phosphatidylinositol phosphoHpase C releases alkaline phosphatase, 5 -nucleotidase, and acetylchoHnesterase from various tissues in soluble form suggesting that these proteins are localized at the periphery of the cell membrane by a phosphatidylinositol-containing Hpid [3, 4]. Further studies on these and other eukaryotic proteins led to the first fuU structural elucidation of a GPI molecule, the Trypanosoma brucei variant surface glycoprotein (VSG) GPI anchor [5, 6]. 

The evidence that phosphatidylinositol has a role in protein anchoring comes from two sources (a) the release of certain membrane proteins following digestion with a phosphatidylinositol-specific phospholipase C and (b) analysis of the anchoring domain of some of these membrane proteins. Examples of proteins believed to be attached thus to membranes include alkaline phosphatase, acetylcholinesterase, 5 -nucleotidase and the variant surface glycoprotein (VSG) from Trypanosoma brucei, (The latter is responsible for the ability of this parasitic protozoan to evade the victim s immune defence system and so cause sleeping sickness.)... 

T. cruzi small mucin-like gene family TcTS, Trypanosoma cruzi trans-sialidase THF, tetrahydrofuran TMSOTf, trimethylsilyl trifluoromethanesulfonate TRR, Thr-rich region TSSA, trypomastigote small surface antigen UDP, uridine diphosphate VSG, variant surface glycoprotein. 

GTPyS guanosine 5 -0-(3-thiotriphosphate) VSG variant surface glycoprotein... 

---