title: The stage-specific 90-kilodalton surface antigen of metacyclic trypomastigotes of Trypanosoma cruzi.
abstract: The 90-kDa antigen, previously identified by the monoclonal antibody 1G7 to be a stage-specific surface protein of metacyclic trypomastigotes of Trypanosoma cruzi, has been further characterized in this study. Experiments of metabolic labeling with [35S]methionine, [2H]mannose and [3H]galactose revealed that the 90-kDa antigen is the main glycoprotein synthesized by metacyclic forms (G strain). Through pulse-chase experiments with [35S]methionine-labeled metacyclic trypomastigotes, it was found that the antigen is synthesized as a 75-kDa precursor polypeptide that is rapidly processed to the mature 90-kDa molecule. When metacyclic trypomastigotes were treated with tunicamycin, the production of 90-kDa antigen was greatly diminished, and the 75-kDa species, which was also expressed on the cell surface, accumulated. Concanavalin A bound strongly to the 90-kDa antigen, but failed to recognize the 75-kDa polypeptide. Treatment of neuraminidase had no effect on the 90-kDa antigen, whereas digestion by endoglycosidase H generated a polypeptide of 82 kDa. Altogether these data indicate that the 90-kDa antigen is a glycoprotein containing N-linked oligosaccharide side chains of the high-mannose type. The 90-kDa glycoprotein may be involved in the process of host cell invasion, since the internalization of metacyclic forms into Vero cells was partially inhibited by monoclonal antibody 1G7.
authors.affiliation: Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, São Paulo, Brazil.
authors.forename: N
authors.initials: N
authors.lastname: Yoshida
authors.forename: S A
authors.initials: SA
authors.lastname: Blanco
authors.forename: M F
authors.initials: MF
authors.lastname: Araguth
authors.forename: M
authors.initials: M
authors.lastname: Russo
authors.forename: J
authors.initials: J
authors.lastname: González
mesh_terms: D000118:Acetylglucosaminidase; D000818:Animals; D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan / Q000096:biosynthesis*; D000954:Antigens, Surface / Q000096:biosynthesis*; D006031:Glycosylation; D007457:Iodine Radioisotopes; D008358:Mannose / Q000378:metabolism; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D008970:Molecular Weight; D009439:Neuraminidase; D011499:Protein Processing, Post-Translational; D014349:Trypanosoma cruzi / Q000276:immunology* / Q000472:pathogenicity; D014709:Vero Cells
chemical_list: D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D000954:Antigens, Surface; D007457:Iodine Radioisotopes; D009439:Neuraminidase; D000118:Acetylglucosaminidase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D008358:Mannose