Discrimination between the nuclear lamin and intermediate filament (cytokeratin/vimentin) proteins of rat hepatic tumor cells by differential solubility and electrophoretic criteria.
1. The major proteins which comprise the high salt/detergent-insoluble cytoskeletal matrix of rat hepatic tumor cells containing abnormal (Mallory body-like) aggregates of intermediate filaments were distinguished on the basis of electrophoretic mobility and differential solubility. 2. Gel electrophoresis of the intermediate filament-enriched cytoskeletal fraction of Mallory body hepatic tumor cells revealed the presence of: (a) intermediate filament proteins typical of cultured liver epithelial cells (cytokeratins A and D, vimentin), (b) some residual actin and, (c) two peptides of Mr = 68,000-72,000. 3. Analysis of the products of filament disassembly/reassembly mixtures indicated that the two Mr = 68,000-72,000 peptide species had the solubility characteristics of nuclear lamins. 4. The presence of nuclear lamin proteins in the high salt/detergent-resistant fraction of cultured liver cells was consistent with the resolution of residual nuclear-like structures in extracted cell monolayers. 5. Thus, while cytokeratin/vimentin-class intermediate filament proteins and nuclear lamins co-isolate from rat liver cells under conditions of high salt/detergent extraction, these two types of cytoskeletal proteins could be distinguished on the basis of their differential solubility and molecular weight.
D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000032:analysis*; D004052:Diethylnitrosamine; D004591:Electrophoresis, Polyacrylamide Gel; D007381:Intermediate Filament Proteins / Q000302:isolation & purification*; D007633:Keratins / Q000302:isolation & purification*; D034882:Lamins; D008113:Liver Neoplasms / Q000032:analysis* / Q000139:chemically induced / Q000473:pathology; D009687:Nuclear Proteins / Q000302:isolation & purification*; D051381:Rats; D012995:Solubility; D014746:Vimentin / Q000302:isolation & purification*
D007381:Intermediate Filament Proteins; D034882:Lamins; D009687:Nuclear Proteins; D014746:Vimentin; D004052:Diethylnitrosamine; D007633:Keratins