The regulatory component of adenylate cyclase from uncoupled S49 lymphoma cells differs in charge from the wild type protein

Abstract

The uncoupled (UNC) variant of the S49 lymphoma possesses the components known to be required for a hormone-sensitive adenylate cyclase system, including receptors for hormones, a guanine nucleotide-binding regulatory protein (G/F), and a catalyst; however, hormones are ineffective in stimulating enzymatic activity in these cells. Two proteins (Mr = 45,000 and 55,000) are labeled with [32P]NAD when wild type or UNC membranes are incubated with the labeled nucleotide and cholera toxin (Johnson, G.L., Kaslow, H.R., and Bourne, H.R. (1978) J. Biol. Chem. 253, 7120-7123). The 45,000-dalton component appears to be a constituent of G/F. Two dimensional electrophoresis of the labeled proteins reveals that both are more acidic when derived from UNC cells.