title: Further characterization of Trypanosoma cruzi GP57/51 as the major antigen expressed by differentiating epimastigotes.
abstract: Study of Trypanosoma cruzi metacyclogenesis under chemically defined conditions showed that the expression of a group of acidic polypeptides with a molecular weight of 45-50 kDa is markedly increased on adhesion of epimastigotes to the culture vessels. Immunochemical analysis revealed that these developmentally regulated polypeptides are structurally related to, and possibly homologous with, a major T. cruzi antigen, namely, GP57/51, a glycoprotein that has recently been characterized as a cysteine proteinase. The differentiation of epimastigotes into metacyclic trypomastigotes is accompanied by a 2- to 5-fold reduction in the concentration of GP57/51 antigen as determined by radioimmunoassays using monoclonal antibodies. Two-dimensional polyacrylamide gel electrophoretic analysis of metabolically labelled parasites indicated that this antigen is synthesized as a precursor with a molecular weight of 60 kDa, which is then processed to a level of 45-50 kDa via the formation of at least one intermediate processing product. The observation that expression of GP57/51-related products increases during epimastigote differentiation suggests an important role for this proteinase during the life cycle of T. cruzi.
authors.affiliation: Fundação Oswaldo Cruz, Dept. Bioquimica e Biologia Molecular, Rio de Janeiro, Brasil.
authors.forename: M C
authors.initials: MC
authors.lastname: Bonaldo
authors.forename: J
authors.initials: J
authors.lastname: Scharfstein
authors.forename: A C
authors.initials: AC
authors.lastname: Murta
authors.forename: S
authors.initials: S
authors.lastname: Goldenberg
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry*; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000737:chemistry*; D008970:Molecular Weight; D011233:Precipitin Tests; D011498:Protein Precursors / Q000737:chemistry*; D011863:Radioimmunoassay; D014349:Trypanosoma cruzi / Q000276:immunology*
chemical_list: D000953:Antigens, Protozoan; D006023:Glycoproteins; D011498:Protein Precursors; D003546:Cysteine Endopeptidases; C073182:GP57-51 antigen, Trypanosoma cruzi