Changes in GTP-dependent fusion and ras-related proteins in membranes from rat hepatocellular carcinomas.
The fusion capacity of rough endoplasmic reticulum membranes isolated from dissected liver tumor nodules of aflatoxin-treated rats was determined by cell free assay to be greater than that of homologous membranes from control liver. In a first attempt to understand the reason for this difference we compared the content of ras-related proteins in rough microsomal fractions and other cell fractions of both dissected tumor nodules and control liver. Using [alpha-32P]GTP blot overlay and densitometric analysis, homogenate, Golgi and rough endoplasmic reticulum fractions from dissected tumor nodules were observed to contain increased amounts of [alpha-32P]GTP binding to ras-related proteins when compared to homologous control fractions. Western blot analysis indicated that ras content was also increased in the tumor fractions. [alpha-32P]GTP-blot overlay using double-dimensional SDS-polyacrylamide gel electrophoresis confirmed quantitative differences in the amount of [alpha-32P]GTP binding to ras-related proteins between fractions from tumor and control tissues and indicated a surprising number of such proteins in each fraction. The data suggest that the changes in ras-related proteins could, in part, account for the enhanced GTP-dependent fusion capacity observed for the tumor-derived membranes.
Département d'Anatomie, Faculté de Médecine, Université de Montréal, Québec, Canada.
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Lanoix
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Paiement
D016604:Aflatoxin B1; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000139:chemically induced / Q000737:chemistry* / Q000503:physiopathology*; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D018870:Endoplasmic Reticulum, Rough / Q000737:chemistry*; D006056:Golgi Apparatus / Q000737:chemistry; D006160:Guanosine Triphosphate / Q000378:metabolism; D007425:Intracellular Membranes / Q000737:chemistry; D008113:Liver Neoplasms / Q000139:chemically induced / Q000737:chemistry* / Q000503:physiopathology*; D008297:Male; D008561:Membrane Fusion; D008862:Microsomes, Liver / Q000737:chemistry; D011485:Protein Binding; D051381:Rats; D011916:Rats, Inbred F344; D013347:Subcellular Fractions / Q000737:chemistry; D018631:ras Proteins / Q000032:analysis* / Q000378:metabolism
D006160:Guanosine Triphosphate; D016604:Aflatoxin B1; D018631:ras Proteins