A membrane-bound protein cofactor (ARF) is required for the cholera toxin-dependent ADP-ribosylation of the stimulatory regulatory component (G(s)) of adenylate cyclase. Improved methods for the purification of ARF from bovine brain are described. ARF has a high-affinity binding site for guanine nucleotides. Binding of GTP or GTPγS to ARF is necessary for the activity of the cofactor; GDP·ARF does not support ADP-ribosylation of G(s). Although the protein as purified contains stoichiometric amounts of GDP, GTPase activity of isolated ARF was not detected. Cholera toxin-dependent activation of adenylate cyclase thus requires two guanine nucleotide binding proteins.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - Dec 1 1986|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology