Purification of a protein cofactor required for ADP-ribosylation of the stimulatory regulatory component of adenylate cyclase by cholera toxin - PubMed (original) (raw)

. 1984 May 25;259(10):6228-34.

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Purification of a protein cofactor required for ADP-ribosylation of the stimulatory regulatory component of adenylate cyclase by cholera toxin

R A Kahn et al. J Biol Chem. 1984.

Free article

Abstract

A factor (ARF) that is required for the cholera toxin-dependent ADP-ribosylation of the stimulatory, GTP-binding regulatory component (Gs) of adenylate cyclase has been purified about 2000-fold from cholate extracts of rabbit liver membranes. ARF is an intrinsic membrane protein with Mr = 21,000. The final product can be resolved into two polypeptides with very similar molecular weights; each of these has ARF activity. The ADP-ribosylation of Gs can now be studied with defined components. GTP and ARF are both necessary cofactors. The data imply that the substrates for the activated toxin are NAD and a GTP X Gs X ARF complex, and the reaction proceeds in a lipid environment. The apparent ability of ARF to bind to the alpha subunit of Gs suggests that it may play another, unknown role in the regulation of adenylate cyclase activity.

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