Effects of GTP,GDP[beta S] and glucose on adenylate cyclase activity of E. coli B.

Adenylate cyclase activity was measured in suspensions of E.coli B, rendered permeable with toluene. The enzyme was activated in a dose-dependent manner by GTP and by its non-hydrolysable analogue, GTP[gamma S]. In contrast, incubation with GDP[beta S], a non-phosphorylatable analogue of GDP, caused a dose-related inhibition of adenylate cyclase; this was partially overcome by addition of GTP. GTP did not relieve, and GDP[beta S] augmented, the non-competitive and dose-related inhibition of E.coli adenylate cyclase by glucose.