Characterization of atrial-natriuretic-factor-receptor-coupled membrane guanylate cyclase from rat and mouse testes

Studies with isolated adrenal cells and mouse testicular cells have supported a mediatory role of cyclic GMP in ANF (atrial natriuretic factor)-dependent steroidogenic signal transduction. This concept has been strengthened by the purification and biochemical characterization of a 180 kDa protein, which appears to contain both ANF receptor and guanylate cyclase activities, from rat adrenocortical carcinoma cells. Utilizing the antibody to 180 kDa membrane guanylate cyclase as a probe, we now demonstrate the direct presence of ANF-dependent membrane guanylate cyclase in mouse and rat testes. The antibody blocks the ANF-dependent guanylate cyclase activity in isolated membranes, and Western-blot analysis of the partially purified enzyme reveals a single 180 kDa protein. The presence of this enzyme in mouse and rat testes, together with its previous demonstration in rat adrenocortical carcinoma, represent an important potential biochemical role for this enzyme in receptor-mediated steroidogenic signal transduction.