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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: It was concluded that hormones as well as fluoride ion decrease the sensitivity of the enzyme toward inhibition by ATP not complexed to magnesium, thereby favoring the formation of the productive Michaelis complex.
93 citations
TL;DR: The finding that activation of specific CRF-binding sites in adrenal tissue stimulates the adenylate cyclase-cAMP system suggest that CRF may have an important regulatory role in various peripheral tissues.
Abstract: Specific binding sites for rat corticotropin-releasing factor (rCRF) are present in rat adrenal medulla, ventral prostate, spleen, liver, kidney, and testis and bovine chromaffin cells in culture. Maximal binding of [125I]rCRF occurred within 25 min at 4 C and was saturable. Scatchard analysis of rCRF binding to rat adrenal membranes and bovine chromaffin cells revealed the existence of two classes of binding sites. One class had a relatively higher apparent affinity and lower number of binding sites, whereas the other class had a relatively lower affinity and higher number of binding sites. CRF induced a dose-related increase in rat adrenal membrane adenylate cyclase activity and cAMP levels in bovine chromaffin cells. Nanomolar concentrations of rCRF maximally stimulated adenylate cyclase activity in rat adrenal membranes and maximally increased cAMP levels in bovine chromaffin cells to 86% and 130% above control values, respectively. The demonstration of specific CRF-binding sites in a variety of peripheral tissues and the finding that activation of specific CRF-binding sites in adrenal tissue stimulates the adenylate cyclase-cAMP system suggest that CRF may have an important regulatory role in various peripheral tissues.
93 citations
TL;DR: Of 12 neuroleptic drugs with reported antipsychotic efficacy, all inhibit stimulation of adenylate cyclase by 40 muM dopamine at micromolar concentrations, and among 14 other structurally related drugs that are not clinically effective as antippsychotic agents, 12 were almost ineffective while two drugs were moderate inhibitors of dopamine-sensitive adenYLate cyclases.
Abstract: Antipsychotic drugs and their clinically impotent congeners were examined as inhibitors of dopamine-sensitive adenylate cyclase (EC 4.6.1.1) in cell-free membrane preparations of the caudate-putamen of rat brain. Of 12 neuroleptic drugs with reported antipsychotic efficacy, all inhibit stimulation of adenylate cyclase by 40 μM dopamine at micromolar concentrations. Among 14 other structurally related drugs that are not clinically effective as antipsychotic agents, 12 were almost ineffective while two drugs were moderate inhibitors of dopamine-sensitive adenylate cyclase.
93 citations
TL;DR: Results indicated a differential requirement for the carboxyl terminus downstream to the palmitoylation site in the coupling with G protein subtypes, i.e. it is required forThe coupling with Gi but not for that with Gq.
93 citations
TL;DR: The interactions of the various components of the adenylate cyclase system are studied by co-reconstituting pure β-adrenergic receptors, pure Ns and Ni, and functionally resolved preparations of the catalyst in phospholipid vesicles.
Abstract: The best understood system for transduction of extracellular messages into intracellular signals is the hormone receptor-coupled adenylate cyclase. In such systems receptors are functionally coupled to the enzyme by two special proteins, termed the stimulatory and inhibitory guanine nucleotide regulatory proteins (Ns and Ni, respectively). These proteins, thought to mediate, respectively, stimulatory and inhibitory influences on the adenylate cyclase, are members of a larger class of heterotrimeric guanine nucleotide regulatory proteins involved in membrane signal transduction. We have studied the interactions of the various components of the adenylate cyclase system by co-reconstituting pure beta-adrenergic receptors, pure Ns and Ni, and functionally resolved preparations of the catalyst in phospholipid vesicles. In the absence of Ni, beta-adrenergic receptor/Ns-mediated catecholamine stimulation of the enzyme is relatively modest (approximately 1.3-fold). Surprisingly, however, when Ni is also present, stimulation increases dramatically (up to 7-8-fold) because of a greater suppression of basal relative to agonist-stimulated enzyme activity. Thus, Ni may actually be required for maximal agonist stimulation as well as for inhibition of the adenylate cyclase.
93 citations