ATP-dependent activation of adenylate cyclase

Incubation of rat liver plasma membranes with MgCl2, ATP, and an ATP-regenerating system at 4 degrees C provides a 4-7-fold persistent activation of adenylate cyclase. Enzyme activation is time-dependent and 48 h of incubation is usually required to achieve maximal stimulation of adenylate cyclase activity. The activation described is not affected by GTP, cAMP, or cGMP, and does not occur when ATP is replaced by a nonphosphorylating analogue, adenyl-5'-imidodiphosphate. In addition to ATP, the activation requires Mg2+ and an ATP-regenerating system. The activation described is not additive with that produced by fluoride and analysis of basal and fluoride activities following extended incubation for 48 h reveals identical activities which decay at the same rate. These results are consistent with our model (11) which invokes phosphorylation-dephosphorylation mechanisms in regulating adenylate cyclase activity.