Purification and characterization of the 180-kDa membrane guanylate cyclase containing atrial natriuretic factor receptor from rat adrenal gland and its regulation by protein kinase C

Abstract

The original concept that cyclic GMP is one of the mediators of the hormone-dependent process of steroidogenesis has been strengthened by the characterization of a 180-kDa protein from rat adrenocortical carcinoma and rat and mouse testes. This protein appears to have an unusual characteristic of containing both the atrial natriuretic factor (ANF)-binding and guanylate cyclase activities, and appears to be intimately involved in the ANF-dependent steroidogenic signal transduction. In rat adrenal glands we now demonstrate: 1) the direct presence of a 180-kDa ANF-binding protein in GTP-affinity purified membrane fraction as evidenced by affinity cross-linking technique and by the Western blot analysis of the partially purified enzyme; 2) that the enzyme is biochemically and immunologically different from the soluble guanylate cyclase as there is no antigenic cross-reactivity of 180-kDa guanylate cyclase antibody with soluble guanylate cyclase; 3) in contrast to the soluble guanylate cyclase, the particulate enzyme is not stimulated by nitrite-generating compounds and hemin; and 4) protein kinase C inhibits both the basal and ANF-dependent guanylate cyclase activity and phosphorylates the 180-kDa guanylate cyclase. These results reveal the presence of a 180-kDa protein in rat adrenal glands and support the contention that: (a) this protein contains both the guanylate cyclase and ANF receptor; (b) the 180-kDa enzyme is coupled with the ANF-dependent cyclic GMP production; (c) the 180-kDa enzyme is biochemically distinct from the nonspecific soluble guanylate cyclase; and (d) there is a protein kinase C-dependent negative regulatory loop for the operation of ANF-dependent cyclic GMP signal pathway which acts via the phosphorylation of 180-kDa guanylate cyclase.