Plasma membrane-associated component(s) that confer(s) cholera toxin sensitivity to adenylate cyclase

Incubation of crude normal rat kidney membranes with activated cholera toxin in the presence of DTP, ATP and NAD results in a 10--20 fold stimulation of adenylate cyclase activity. Optimal choleragen activation f the cyclase is shown to be dependent upon the presence of a plasma membrane-associated reconstituting activity, which can be dissociated from the membranes by washing with 10 mM potassium phosphate buffer, pH 7.5, containing 5 mM EDTA and 0.1 mM dithiothreitol. choleragen-catalyzed ADP ribosylation of plasma membrane substrate proteins also requires the presence of reconstituting activity factor. Sephadex G-150 filtration of solubilized reconstituting activity shows a peak activity eluting in the region corresponding to a protein with a molecular weight of approx. 13,000. Reconstituting activity is eluted from DEAE-cellulose at a salt concentration of 40--100 mM KCl. This active factor is not destroyed by trypsin treatment or by boiling for 30 min. These observations indicate that an endogenous membrane-associated factor, along with GTP, may be involved in modulating the ability of choleragen to activate adenylate cyclase.