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Cyclase

About: Cyclase is a research topic. Over the lifetime, 10162 publications have been published within this topic receiving 388566 citations.


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Journal ArticleDOI
TL;DR: A dual regulation of oocyte phosphodiesterase and adenylate cyclase by insulin and insulin-like growth factor 1 is demonstrated.

101 citations

Book ChapterDOI
TL;DR: This chapter describes multiple facets of the modulation of growth by cyclic AMP, finding that due to the negative cooperativity of the phosphodiesterase system, these inhibitors are much more efficient in increasing the cAMP response to activators of adenylate cyclase than in increasing basal levels of cAMP.
Abstract: Publisher Summary This chapter describes multiple facets of the modulation of growth by cyclic AMP (cAMP). The successes in elucidating the functions of cell-transforming proteins encoded by various oncogenes and the demonstration of antioncogenes have shed light on the assumption that cancers mostly develop from alterations of growth control mechanisms, normally involved in homeostasis, tissue repair, and development. cAMP is the first identified intracellular second messenger of hormone action. Pharmacological and genetic tools used to manipulate the CAMP-PKA cascade are summarized in the chapter. Forskolin, a plant diterpene, activates vertebrate adenylate cyclase directly and enhances its response to activated GS, thus to the receptors that regulate GS. Inhibitors of cyclic nucleotide phosphodiesterases by inhibiting the catabolism of cAMP also raise cAMP levels. It is found that due to the negative cooperativity of the phosphodiesterase system, these inhibitors are much more efficient in increasing the cAMP response to activators of adenylate cyclase than in increasing basal levels of cAMP.

101 citations

Journal ArticleDOI
TL;DR: The evidence for hormone receptors in relation to the adenyl cyclase system is reviewed, a detailed description of the interaction of ACTH with its physiological receptors in adrenal cortical tissue is presented, and the ACTH system is used as a model to speculate further on the nature and role of hormone receptors.
Abstract: Since the original demonstration that epinephrine stimulates the adenyl cyclase system of liver cells,l numerous hormonal substances have been shown to act by altering the activity of cell membrane-bound adenyl cyclase in their respective target tissues.2 Two general phenomena related to the interaction of hormones and adenyl cyclase have become clear. First, the enzyme is very widespread, occurring in almost all mammalian tissues examined except erythrocytes. Second, in any given tissue only a very limited number of hormones (often just one) influence the activity of the enzyme. This latter phenomenon is referred to as “hormone specificity.” Thus, only TSH stimulates thyroid adenyl cyclase,:’ only ACTH stimulates adrenal adenyl c y ~ l a s e , ~ and so forth. The specific cell membrane structures responsible for this great hormone specificity in each tissue have been referred to as receptors.5 Whereas the catalytic function of converting ATP to cyclic AMP resides in the adenyl cyclase enzyme, the discriminatory function of permitting only a narrow range of hormones to interact with the enzyme resides in the receptors. The exact relationship of these “catalytic” and receptor functions of the adenyl cyclase system has been the subject of much speculation.5 In fact, it is only recently that physicochemical proof of the existence of these receptors has been obtained. The purpose of this paper is to (1) review briefly the evidence for hormone receptors in relation to the adenyl cyclase system, (2) present a detailed description of the interaction of ACTH with its physiological receptors in adrenal cortical tissue, and (3 ) use the ACTH system as a model to speculate further on the nature and role of hormone receptors.

101 citations

Journal ArticleDOI
TL;DR: The affinity of YM-09151-2 for D2-receptors with a Ki value of 0.1 nM was more than 1000-times higher than that for the other receptors and dopamine-sensitive adenylate cyclase, and it was the greatest among the neuroleptics tested.

101 citations

Journal ArticleDOI
TL;DR: The results show that in the membrane of the fat cell a single catalytic unit of adenyl cyclase is coupled to distinctive selectivity sites for three lipolytic hormones.
Abstract: A large number of hormones, of diverse molecular structure, evoke characteristic responses in target cells via the intermediary 3′,5′-AMP, the specificity of hormone action upon cell type being achieved by selective stimulation of adenyl cyclase. In the fat cells of rat adipose tissue, adenyl cyclase is stimulated by a number of hormones of disparate molecular structure, posing the question whether this cell type posesses multiple cyclase systems with distinctive specificities for individual hormones, or a single cyclase with broad specificity to a variety of hormones. Studies of the stimulatory effects of adenocorticotropin, glucagon, and epinephrine upon the adenyl cyclase of the rat fat cell “ghosts” (plasma membrane sacs) have shown that distinctive selectivity sites for each of these hormones can be differentiated. The β-adrenergic blocking agent Ko 592 abolished the stimulatory effect of epinephrine without influencing adenocorticotropin or glucagon; Ca was required for adenocorticotropin action, but not for glucagon or epinephrine. Dose-response curves show that the affinity of hormones to the cyclase system was in the order: glucagon > adenocorticotropin ≫ epinephrine; the magnitude of cyclase activation by maximal doses of hormones had a reversed order. Combinations of maximal doses of hormones failed to produce additive stimulation. The results show that in the membrane of the fat cell a single catalytic unit of adenyl cyclase is coupled to distinctive selectivity sites for three lipolytic hormones.

101 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202324
202257
202145
202048
201939
201856