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MARY HUNZICKER-DUNN, DENNIS DERDA, RICHARD A. JUNGMANN, LUTZ BIRNBAUMER, Resensitization of the Desensitized Follicular Adenylyl Cyclase System to Luteinizing Hormone, Endocrinology, Volume 104, Issue 6, 1 June 1979, Pages 1785–1793, https://doi.org/10.1210/endo-104-6-1785
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LH-induced desensitization of the adenylyl cyclase system in a cell-free membrane preparation from preovulatory porcine follicles exhibits a critical dependence upon Mg and ATP (1). The membrane-rich preparation was found to contain endogenous cAMP-dependent and cAMP-independent protein kineses as well as phosphoprotein phosphatases. Endogenous phosphatase activity was enhanced by Mn2+ and dithiothreitol. The addition of either Mn2+ or dithiothreitol to the porcine follicular membrane preparation incubated under desensitizing conditions promoted a specific concentration-dependent reversal of the LH-induced desensitization of the adenylyl cyclase system. The addition of exogenous phosphoprotein phosphatase, partially purified from porcine follicular cytosol, also reversed LH-induced desensitization in a concentration-dependent manner. Boiling of the phosphatase preparation prevented reversal of desensitization. The addition of either exogenous beef heart cAMP-dependent protein kinase or heat-stable protein kinase inhibitor did not modify LH-induced desensitization of the follicular adenylyl cyclase system. These results provide indirect evidence that while LH-induced desensitization is not mediated by a cAMP-dependent protein kinase, reversal of desensitization can be promoted by activation of endogenous phosphatase and the addition of a homologous phosphatase preparation.