Trypanosoma cruzi:The Tc-85 Surface Glycoprotein Shed by Trypomastigotes Bears a Modified Glycosylphosphatidylinositol Anchor

Cloning of a Surface Membrane Glycoprotein Specific for the Infective Form of Trypanosoma cruzi Having Adhesive Properties to Laminin

“…(23,24). The presence of N-glycosylation and GPI anchor insertion sites is in accordance with previous observations showing that Tc-85 is a GPI-anchored membrane glycoprotein (33,34) with N-linked carbohydrates (35,36). The Tc85-11 polypeptide has 12 putative N-glycosylation sites as well as two signal peptides, one at the amino-terminal portion of the molecule, which directs the protein to the endoplasmic reticulum, and the other at the carboxyl-terminal portion for anchor insertion (shown in Fig.…”

“…Refs. 23 and 24), it is safe to generalize that all members of the family are indeed membrane GPIanchored glycoproteins, since an N-linked oligosaccharide anthena (35,36) and a lysoalkylphosphatidylinositol anchor (33,34) have been chemically demonstrated as part of the Tc-85 glycoprotein molecules. Another GPI-anchored glycoprotein from metacyclic trypomastigotes with adhesive properties to cells also belongs to the gp85/trans-sialidase family (40).…”

Lipids shed into the culture medium by trypomastigotes of Trypanosoma cruzi

“…This may be related to the shedding of various important proteins of the trypomastigote stage such as SAPA (Affranchino et al 1989, Pollevick et al 1991, Agusti et al 1997 or Tc-85 (Couto et al 1993, Abuin et al 1996 both being anchored by a glycosylphosphatidylinositol (GPI) to the surface membrane. It has been speculated that GPI-anchored proteins partition preferentially in plasma membrane domains enriched in certain membrane constituents.…”

Relevant glycoconjugates on the surface of Trypanosoma cruzi

“…The fact that Tc-85 labeled with palmitic acid is found in the culture medium suggests that shedding of the glycoprotein occurs without GPI cleavage, contrary to other molecules where anchor cleavage was directly implicated in molecule liberation from the membrane. Shed Tc-85 could not be hydrolysed by phospholipase C, suggesting a modification at the inositol ring which has been proved to be an esterification by palmitic acid (Abuin et al 1996b). …”