The Drosophila proteasome undergoes changes in its subunit pattern during development

The two-dimensional electrophoretic protein subunit pattern of the proteasome, which is a mulifunctional non-lysosomal proteinase, was analyzed throughout the development of Drosophila melanogaster. The experiments show that the proteasome is already present in early embryos and its characteristic gross morphology as judged by the outer diameter of 12 nm and the inner depression of 3 nm remains unaltered. The electrophoretic analysis of the enzyme subunits demonstrates that the proteasome undergoes, dependent on development, alterations in its protein composition. The most simple subunit pattern is observed in Schneider's S-3 tissue culture cells and early embryos while with ongoing fly development the subunit pattern of the proteasome becomes increasingly complex. 32P-Labeling and immunoblotting experiments indicate that post-translational modification of the subunits must in part be responsible for the development-dependent diversification of the subunit pattern. Our data raise the possibility that the in vivo proteolytic activity and the in vivo substrate specificity of the proteasome may be regulated by modification of its subunit composition during fly development.     

Generation of in silico predicted coxsackievirus B3-derived MHC class I epitopes by proteasomes

Amino Acids - Proteasomes are known to be the main suppliers of MHC class I (MHC-I) ligands. In an attempt to identify coxsackievirus B3 (CVB3)-MHC-I epitopes, a combined approach of in silico...     

Presence of Trypanosoma cruzi antigen on the surface of both infected and uninfected cells in tissue culture

LLC-MK2 cell monolayers infected with Trypanosoma cruzi were shown by immunofluorescence to present parasite antigens on the surface of both parasitized and non-parasitized cells after completion of the first intracellular cycle and rupture of infected cells. The cell-culture supernatant fluid at this stage, as well as the supernatant fluid of parasites left overnight in culture medium were concentrated and contained antigen capable of binding to uninfected cell monolayers. The origin of this antigen, as well as its eventual role in the pathogenesis of Chagas' disease, are discussed.