Topic
Cyclase
About: Cyclase is a research topic. Over the lifetime, 10162 publications have been published within this topic receiving 388566 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: Cyclic AMP may play a crucial role in the regulation of platelet phospholipase acitivity, and this could explain at least in part the inhibition of aggregation caused by substances which, like prostacyclin, raise the levels of cyclicAMP.
192 citations
TL;DR: The data strongly suggest that both the hormone- and guanine nucleotide-induced adenylate cyclase inhibitions in cyc− cells are mediated by Ni and that the mechanisms of activation and inactivation of Ni are similar to those established for Ns.
Abstract: The cyc− variants of S49 lymphoma cells have served as powerful tools for studying the components and mechanisms of hormone-induced adenylate cyclase stimulation, as these cells are deficient in the guanine nucleotide regulatory site (Ns) mediating hormone, guanine nucleotide, cholera toxin and fluoride-induced stimulations of the enzyme1. Because of this deficiency, membranes of these cells have been used for reconstitution of the system by inserting the coupling component derived from other cell types2–4. The hormone-sensitive adenylate cyclase is not only stimulated by hormones but can also be inhibited by a wide variety of hormones and neurotransmitters5–8, and there is some evidence that hormonal inhibition may be mediated by a distinct guanine nucleotide regulatory site5–8. Studies in cyc− cells lacking a functional Ns may therefore answer this unresolved, important question. We have recently observed9 that stable GTP analogues can inhibit cyc− adenylate cyclase stimulated by purified, preactivated Ns or forskolin, which can activate adenylate cyclase even in the absence of a functional Ns (ref. 10). The data indicated that these Ns-deficient cells contain an inhibitory guanine nucleotide site, Ni. To strengthen this concept, we investigated whether the cyc− adenylate cyclase can be inhibited by a hormone. We report here that somatostatin decreases cyclic AMP levels in cyc− cells, inhibits the forskolin-stimulated adenylate cyclase and causes a concomitant increase in a high affinity GTPase activity in cyc− membranes. The data strongly suggest that both the hormone- and guanine nucleotide-induced adenylate cyclase inhibitions in cyc− cells are mediated by Ni and that the mechanisms of activation and inactivation of Ni are similar to those established for Ns.
190 citations
190 citations
TL;DR: It is concluded that cyclic AMP is necessary for the normal utilization of a number of carbon sources by E. coli, because it is required for the synthesis of enzymes involved in their metabolism.
190 citations
TL;DR: Data suggest that adenylate cyclase activation is a function of receptor occupancy, and that the time required to reach maximum activation is similar to that needed to reach an equilibrium value for [3H]vasopressin binding at the same concentration.
190 citations