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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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TL;DR: There was a satisfactory correlation between the antidiuretic activities of the peptides tested in the rat and their abilities to activate the adenylate cyclase present on renal membranes.
Abstract: Membranes prepared from the medullopapillary portion of pig and rat kidneys were used to test the relative abilities of 11 arginine-vasopressin structural analogues to activate adenylate cyclase and to inhibit [3H]lysine-vasopressin binding to these membrane preparations. The analogues tested were: [1-deaminopenicillamine, 2-O-methyltyrosine]-arginine-vasopressin; [1-deaminopenicillamine]arginine-vasopressin; [1-deaminopenicillamine, 4 valine, 8-D-arginine]-vasopressin (dP-V-DAVP); [8-D-arginine]-vasopressin; [2-O-methyltyrosine]arginine-vasopressin; [4-valine, 8-D-arginine]-vasopressin; [4-valine]arginine-vasopressin; deamino [4-threonine, 8-D-arginine]-vasopressin; deamino [8-D-arginine]-vasopressin; deamino [4-valine, 8-D-arginine]-vasopressin; [1(β-mercapto-β,β-cyclopentamethylene propionic acid), 4-valine, 8-D-arginine]-vasopressin (cyclo-dV-DAVP). Cyclo-dV-DAVP behaved like a competitive inhibitor of vasopressin-induced adenylate cyclase activation. The apparent Ki values were 10 and 310 nM for the rat and pig systems, respectively. This peptide is the most active antagonist described so far. dP-V-DAVP behaved like a competitive inhibitor on the pig system (Ki = 2.9 µM) and was found to produce a maximal enzyme activation that was 75% of that induced by arginine-vasopressin in the rat system (Kact = 3.7 nM). In both the rat and pig systems there was a good correlation between the Kbind values for binding to renal membranes and the corresponding Kact or Ki values for the adenylate cyclase response. The structural requirements for binding to the pig renal receptor and to the rat renal receptor were found to be different. When one takes into account for metabolic stability of the ADH analogues tested (as estimated by the relative duration of the antidiuretic response), there was a satisfactory correlation between the antidiuretic activities of the peptides tested in the rat and their abilities to activate the adenylate cyclase present on renal membranes.
123 citations
TL;DR: It is reported that activation of μ-opioid receptors directly decreases the N-type calcium-channel current in a differentiated, human neuroblastoma cell line (SHSY5Y).
Abstract: The predominant consequences of mu-opioid-receptor activation are depression of both neuronal activity and transmitter release. Mu-Opioid agonists have previously been observed to increase a potassium conductance and to inhibit adenylate cyclase. We now report that activation of mu-opioid receptors directly decreases the N-type calcium-channel current in a differentiated, human neuroblastoma cell line (SH-SY5Y). The coupling between the mu-opioid receptor and the calcium channel involves a pertussis toxin-sensitive G protein and is independent of changes in adenylate cyclase activity. The inhibition of the calcium-channel current is voltage dependent because it is largely overcome by strong membrane depolarization. It is not associated with changes in the kinetics of current inactivation. Therefore, the mu-receptor belongs to the superfamily of G-protein-coupled, inhibitory neurotransmitter receptors which modulate the activity of calcium and potassium channels and adenylate cyclase.
123 citations
TL;DR: It is suggested that intracellular cyclic AMP may act as the "second messenger" in the regulation of the lower esophageal sphincter relaxation in the intact, lightly anesthetized opossum.
Abstract: A B S T R A C T The intravenous injection of prostaglandin E1 (PGE1) causes a dose-dependent relaxation of the lower esophageal sphincter (LES) in the intact, lightly anesthetized opossum. The action of PGE1 is not inhibited by the drugs that produce muscarinic or nicotinic cholinergic antagonism or alpha and beta adrenergic antagonism in the doses that inhibited the action of respective agonists. Moreover, this action is not affected by exogenous gastrin pentapeptide. The action of PGE1 on the LES is mimicked by isoproterenol, theophylline ethylenediamine, and dibutyryl cyclic AMP. Both theophylline, a phosphodiesterase inhibitor, and isoproterenol, an adenyl cyclase stimulator, added to the action of PGE1. On the other hand, adenyl cyclase inhibitor nicotinic acid, as well as phosphodiesterase stimulator, imidazole inhibited its action. Further, both nicotinic acid and imidazole inhibited the degree of LES relaxation produced by esophageal distension. These studies suggest that intracellular cyclic AMP may act as the "second messenger" in the regulation of the lower esophageal sphincter relaxation.
122 citations
TL;DR: The functional consequences of the cholesterol filipin reaction in erythrocyte membranes are heterogeneous and the relevant complex formation was shown not to involve lysis and disintegration and to occur in that part of the membrane which is probed by the hydrophobic dye perylene.
122 citations
TL;DR: This work examined the G activities of EP3α, EP3β, and the mutant receptor, in which the carboxyl-terminal tail was truncated at the splicing site, and found that alternative splicing produced two isoforms with different carboxesyl- terminal tails and with different constitutive activity.
122 citations