Modulation of adenylate cyclase activity in bovine lens epithelial cells.

Adenylate cyclase activity of bovine lens epithelial cells is activated by guanine nucleotides or fluoride. Additional activation to that of guanylylimidodiphosphate [Gpp(NH)p] was induced by isoproterenol. Insulin was found to inhibit adenylate cyclase activity. Adenosine at low concentrations (5-50 nM) increased adenylate cyclase activity, while at high concentrations it lowered the activity of the enzyme. The occurrence of R and P adenosine sites in lens epithelial cells is suggested. Like other tissues, lens epithelial cells possess a transduction system (adenylate cyclase-G protein complex) for external messages.