Ubiquitin-mediated proteolysis centers in HeLa cells: indication from studies of an inhibitor of the chymotrypsin-like activity of the proteasome.

摘要: HeLa cells growing in vitro were treated with the peptidyl aldehyde inhibitor of chymotrypsin-like activity proteasome N-benzyloxycarbonyl-Ile-Glu(O-t-butyl)-Ala-leucinal (PSI). Immunofluorescence studies revealed formation massive perinuclear aggregates rich ubiquitin and proteasomal antigens, which on ultrastructural level appeared as electron-dense material, usually vicinity Golgi cisternae. Histochemical disclosed that these contained protein-rich detected by amido black staining, while unusual accumulations lipids, carbohydrates, or nucleic acids not present. Inhibition protein synthesis cycloheximide prevented aggregates, whereas microtubule disruption nocodazole induced a dispersion aggregates. We hypothesize PSI treatment correspond to proteasome-substrate complexes well-defined region, where proteolytic processes ubiquitin-proteasome pathway seem be somehow centered. propose call this region proteolysis center.