Abstract
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) |
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Pages (from-to) | 7906-7911 |
Number of pages | 6 |
Journal | Journal of Biological Chemistry |
Volume | 261 |
Issue number | 17 |
State | Published - 1986 |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology