3T3C2 mouse fibroblasts rendered permeable to (α-32P)NAD+ show cholera toxin-dependent labeling of a 45,000 m.w. protein and of a doublet of polypeptides around 52,000 m.w. These same bands are ADP-ribosylated in broken cells. Membranes prepared from pigeon erythrocytes pretreated with choleragen show a decrease in subsequent cholera toxin-specific ADP-ribosylation of a 43,000 m.w. polypeptide. Both whole cell and broken cell adenylate cyclase activation and toxin-specific ADP-ribosylation are reversed specifically by low pH and high concentrations of toxin and nicotinamide in all systems. Thus ADP-ribosylation appears to be relevant to the molecular action of choleragen in whole cells as well as in broken cells.
|Number of pages||12|
|State||Published - Apr 28 1980|
Bibliographical noteFunding Information:
The functional correlation between the labeling of the specific bands and the activation of adenylate cyclase was elegantly made by the separation of the solubilized radiolabeled 43,000 m.w. polypeptide from pigeon erythrocytes adenylate cyclase by affinity chromatography on a GTP-Sepharose column (ii) and by reconstitution studies using mutant $49 lymphoma cells (13). Further' support for the relevance of the 43,000 m.w. ADP-ribosylated polypeptide for the adenylate cyclase activation was provided by the toxin-dependent partial reversal of the stimulated enzyme activity, the subsequent reappearance of NaF sensitivity, and the removal of 32p from the 43,000 m.w. polypeptide (ll,12).
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ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology (all)
- Pharmacology, Toxicology and Pharmaceutics (all)