Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In purified rat pancreatic plasma membranes, (D-Phe4)PHI interacts as a selective VIP agonist for rat pancreatic VIP-preferring receptors, based on binding selectivity and adenylate cyclase activation, therefore allowing us to discriminate between the participation of VIP-preferring and secretin-preferring receptors in VIP stimulation. VIP-preferring receptors also bind GRF. They rely on disulfide bridges for their functional integrity. Their coupling with adenylate cyclase, based on the intrinsic activity of VIP analogues, is poor when compared to that of hepatic VIP receptors. In fresh rat liver plasma membranes, high-affinity VIP receptors are specifically labeled with [125I]helodermin and [125I]His1, D-Ala NLeu27)GRF and are well coupled to adenylate cyclase while low-affinity VIP receptors are not. The first subtype of VIP receptors is highly responsive to guanyl nucleotides and is easily altered by dithiothreitol. Only after freezing and thawing are low-affinity hepatic VIP receptors coupled to adenylate cyclase. Concerning the chemical characterization of VIP receptors, 66- and 35-kDa peptides are detected after specific [125I]VIP cross-linking with double agents in rat pancreatic membranes. In contrast, in intact pancreatic acini, the main source of radioactivity has a molecular mass of 130-180 kDa (with no contribution of intramolecular disulfide bridges), and an 80-kDa peptide is also detectable. The 66-kDa species in membranes can conceivably derive from the 80-kDa species observed in intact cells. Its molecular mass is higher than that of the 56-kDa [125I]VIP cross-linked protein previously observed in rat liver membranes. Besides, species differences between rat and guinea pig pancreas are also evident.
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PMID:Vasoactive intestinal peptide receptors in pancreas and liver. Structure-function relationship. 283 79

Four intestinal cell lines derived from rat fetuses at 19 days of gestation were successfully propagated after electroporation in the presence of different recombinant DNAs containing the viral oncogenes E1A from Adenovirus 5 and large T from SV40 or Polyoma. These immortalized intestinal cells, designated SLC, possess several properties observed in the parent cells of this tissue, including the expression of cytoplasmic villin, enkephalinase and retention of VIP receptors. In contrast, histamine elevated cAMP levels in the SLC cell lines only. The data suggest that the transfection of fetal rat intestinal cells by E1A and large T is associated with the induction of functional histamine receptors coupled with the Gs/Gi regulatory proteins of adenylate cyclase.
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PMID:Expression of histamine and vasoactive intestinal peptide (VIP) receptors in immortalized rat fetal intestinal cells. 283 64

In this study we have characterized and compared the regulation of the HT29 cell vasoactive intestinal peptide receptor/adenylate cyclase system (VIP-R/AC) by the VIP-R agonist peptide histidineisoleucineamide (PHI) and by activators of protein kinase C (PKC) including phorbol 12-myristate, 13-acetate (PMA) and mezerein. Preincubation with either PHI or PKC activator decreased maximum VIP-stimulated AC activity and decreased the number of cell surface VIP-R. A [125I]VIP binding assay using solubilized VIP-R of the plasma membrane and light vesicle fractions from sucrose density step gradients was developed as a more direct measure of VIP-R internalization. Preincubation with PHI or PMA decreased plasma membrane fraction [125I]VIP binding and increased binding in the light vesicle fraction, thus providing the most direct evidence to date for translocation of VIP-R per se from the plasma membrane to another, presumably intracellular, compartment. Two experimental approaches differentiated between agonist and PKC activator regulation of VIP-R/AC. The protein kinase inhibitors H-7 and staurosporine blocked mezerein-, but not PHI-, induced losses of cell surface VIP-R. Also, down-regulation of PKC did not block PHI-induced loss of cell surface VIP-R. Thus, although both agonist and PKC activators can lead to desensitization and internalization of VIP-R, PKC is apparently not involved in the mechanisms of agonist-induced desensitization.
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PMID:Vasoactive intestinal peptide receptor/adenylate cyclase system: differences between agonist- and protein kinase C-mediated desensitization and further evidence for receptor internalization. 284 20

We have investigated VIP-induced relaxation and cyclic AMP accumulation in rat thoracic aorta strips, and the importance of endothelium to both actions. The relaxation was greatly attenuated by removal of endothelium, but was unaltered by cyclo-oxygenase or lipoxygenase inhibitors. Similarly, cyclic AMP formation was nearly abolished with loss of endothelium, but was largely unaffected by inhibitors of arachidonate pathways, cytochrome P450 or guanylate cyclase. VIP may stimulate the release of a diffusible factor from endothelium (an EDRF), which activates adenylate cyclase and relaxes aortic smooth muscle.
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PMID:Vasoactive intestinal peptide evokes endothelium-dependent relaxation and cyclic AMP accumulation in rat aorta. 285 61

The interaction between two neuropeptides, VIP and TRH, was studied. The TRH receptor binding ability was examined using intact GH3 cells and its membrane fraction. The TRH binding ability decreased when intact cells were preincubated with VIP, forskolin or db-cAMP, but not when the membrane fraction was treated with these agents. The binding was reduced only when the membrane fraction was treated with catalytic subunit of cAMP dependent protein kinase (A-kinase). These results indicate that the binding ability of TRH receptors, which are linked to inositol phospholipid metabolism, is suppressed when A-kinase increases due to activation of the adenylate cyclase or its dependent system. This, in turn, suggests the presence of a communication via a cytoplasmic factor (probably A-kinase) between the two principal second messenger systems in the cell.
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PMID:Receptor-stimulated system mediated interactions of neuropeptides in GH3 cells. 285 60

The effect of GRF adenylate cyclase activation was studied in normal human, bovine and rat pituitary tissues. Human GRF (hGRF) activates adenylate cyclase in normal human pituitary membrane preparations in a concentration dependent manner (ED5 0 = 10(-11) M). In bovine pituitary cells hGRF stimulates GH secretion into the medium (ED5 0 = 7 X 10(-12) M) and activates adenylate cyclase (ED5 0 = 10(-11) M). In normal rat pituitary cells in monolayer culture, rat GRF (rGRF) stimulates adenylate cyclase (ED5 0 = 3 X 10(-11) M). In normal human pituitary membrane preparations and in normal rat pituitary cells in culture, somatostatin inhibits GRF-stimulated adenylate cyclase in a non-competitive manner, while it does not affect basal (i.e. non-stimulated) adenylate cyclase levels. VIP, a peptide which is structurally homologous to hGRF and rGRF is a weak GRF-agonist and activates adenylate cyclase in human and rat pituitary preparations at concentrations greater than 10 nM.
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PMID:GRF is a highly potent activator of adenylate cyclase in the normal human, bovine and rat pituitary: interaction with somatostatin. 285 17

GH3 cells were used to study the effect of rat growth hormone-releasing factor on adenylate cyclase activity and its interaction with somatostatin. Rat GRF stimulates adenylate cyclase activity (ED5 0 = 6 X 10(-8) M) and somatostatin-14 inhibits this GRF-stimulated activity in a non-competitive manner without affecting the basal enzyme levels. Inhibition by somatostatin-14 is observed at concentrations as low as 10(-11) M and the half-maximal effect is obtained with 10(-8) M. Somatostatin-28 is more potent than SS-14 and has an ED5 0 of 3 X 10(-11) M. VIP is more active than rat GRF in stimulating adenylate cyclase activation. We conclude that in GH3 cells rat GRF behaves as a partial VIP agonist by interacting with VIP-preferring receptors and its effects are inhibited by somatostatin.
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PMID:Somatostatin inhibits growth hormone-releasing factor-stimulated adenylate cyclase activity in GH, cells. 285 18

We have examined the mechanisms by which S-14 inhibits pituitary hormone secretion in a homogeneous cell population: the clonal GH4C1 cell line. The S-14 receptor in GH4C1 cells is coupled to Ni, a guanine nucleotide binding protein which mediates S-14-induced inhibition of VIP-stimulated adenylate cyclase activity, cyclic AMP production and hormone secretion. In addition, a functional Ni is required for S-14 to inhibit basal hormone secretion, an action which appears to be independent of cyclic AMP concentrations. Accumulating evidence indicates that the mechanism of S-14 action in somatotrophs is similar to that in GH4C1 cells. Although S-14 consistently inhibits basal GH secretion, its effects on basal cyclic AMP levels in normal pituitary cells are variable and often not significant (10-14). In contrast, S-14 inhibits prostaglandin and growth hormone releasing factor (GRF) stimulated cyclic AMP accumulation and GH release in parallel. Furthermore, S-14 partially blocks prostaglandin and GRF stimulation of adenylate cyclase activity in rat anterior pituitary membranes. Finally, pretreatment of primary cultures of rat pituitary cells with IAP antagonizes S-14 inhibition of both basal and GRF-stimulated GH release.
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PMID:Mechanisms of somatostatin action in pituitary cells. 286 38

We used a GH3 cell-line to compare the effects of rat GRF (rGRF) and VIP on the adenylate cyclase activity and to determine on what subunit the site of action of these two peptides is. In the GH3 cell-line, VIP was more potent than rGRF to stimulate adenylate cyclase activity. The stimulatory effects of rGRF and forskolin were additive. Cholera toxin decreased the apparent potency of these peptides and pertussis toxin reversed the inhibition by somatostatin of their adenylate cyclase stimulation. We conclude that rGRF acts on the regulatory subunit Ns, different from the regulatory subunit Ni on which somatostatin is suggested to be acting and that, in the GH3 cells, rGRF stimulates adenylate cyclase through VIP-preferring sites.
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PMID:Somatocrinin stimulates adenylate cyclase-Ns regulatory subunit in a GH3 cell-line: comparison with VIP. 287 42

These studies were performed to examine whether prostaglandin E2 stimulates intestinal epithelial secretion via a receptor-mediated or non-receptor-mediated activation of adenylate cyclase. Solubilization of epithelial cell adenylate cyclase with Lubrol PX, which separates the receptor moiety of the cyclase from the remainder of the complex, inhibited the prostaglandin E2 stimulation of the cyclase. A similar result was obtained with VIP, which activates adenylate cyclase via a receptor-mediated mechanism, whereas fluoride, gamma S-GTP, and forskolin, which activate the cyclase via non-receptor-mediated mechanisms, all stimulated solubilized adenylate cyclase. In addition, prostaglandin E2 and VIP both showed a dependence on GTP for adenylate cyclase stimulation while fluoride and forskolin did not. These data suggest that prostaglandin E2 activates intestinal mucosal adenylate cyclase by a receptor-mediated mechanism. The presence of such receptors lends support to the possibility that prostaglandins have a physiological role in the control of mucosal transport.
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PMID:Evidence that PGE2 stimulates intestinal epithelial cell adenylate cyclase by a receptor-mediated mechanism. 287 97


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