title: Trypanosoma cruzi: the Tc-85 surface glycoprotein shed by trypomastigotes bears a modified glycosylphosphatidylinositol anchor.
abstract: Tc-85, an 85-kDa surface glycoprotein specific for the trypomastigote stage of Trypanosoma cruzi, has been implicated in the invasion of host cells by the parasite. Radioactive palmitic acid was incorporated into Tc-85 immunoprecipitated from the culture medium with the H1A10 monoclonal antibody, suggesting that shedding occurs with Tc-85 bearing its GPI anchor. In contrast to the glycoprotein remaining in the parasites, the glycosylphosphatidylinositol moiety in shed Tc-85 is resistant to phosphatidylinositol phospholipase C and becomes susceptible to the enzyme following alkali treatment. An alkylglycerol was identified by thin layer chromatography of an ether extract after the enzymatic reaction. Resistance to cleavage by phospholipase C is due to fatty acid esterification of the inositol residue in shed Tc-85. This is the first example of inositol modification in anchors from a glycoprotein of Trypanosoma cruzi.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Brazil.
authors.forename: G
authors.initials: G
authors.lastname: Abuin
authors.forename: A S
authors.initials: AS
authors.lastname: Couto
authors.forename: R M
authors.initials: RM
authors.lastname: de Lederkremer
authors.forename: O L
authors.initials: OL
authors.lastname: Casal
authors.forename: C
authors.initials: C
authors.lastname: Galli
authors.forename: W
authors.initials: W
authors.lastname: Colli
authors.forename: M J
authors.initials: MJ
authors.lastname: Alves
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015153:Blotting, Western; D002855:Chromatography, Thin Layer; D006023:Glycoproteins / Q000737:chemistry*; D017261:Glycosylphosphatidylinositols / Q000032:analysis*; D008565:Membrane Proteins / Q000737:chemistry*; D011233:Precipitin Tests; D015800:Protozoan Proteins / Q000737:chemistry*; D014349:Trypanosoma cruzi / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D015800:Protozoan Proteins