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 this study we characterize the beta 2 adrenergic dependent adenylate cyclase system of epidermoid carcinoma cells (A431). We show that the cells synthesize up to 130,000 [125I]-cyanopindolol binding sites per cell when freshly plated, a value which decreased to 40,000-50,000 receptors/cell within 24 hr. Production of this high number of receptors can be strongly inhibited by actinomycin D. We confirm and extend the fact that these beta-adrenoceptors are of the beta 2-subtype, using selective ligands, photoaffinity labeling with [125I]CYP-diazirine identified two protein subunits: p59 and p72, the beta 2-adrenoceptor dependent adenylate cyclase desensitizes with half-life of 2.2 +/- 0.3 min whereas the loss of [125I]CYP binding from the cell surface requires longer exposure times to the agonist, phorbol-12-myristate-13-acetate (PMA) has no effect on the desensitization process nor does it have any effect on the modulation of beta-agonist affinity by guanyl nucleotides. Rather, PMA was found to stimulate adenylate cyclase activation by forskolin. We conclude that protein kinase C is probably not involved in the beta-adrenoceptor desensitization in this cell line.
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PMID:Characterization of the beta 2-adrenoceptor-dependent adenylate cyclase of A431 epidermoid carcinoma cells. 303 91

The function of the pars tuberalis as a mediator of the action of melatonin remains elusive. As a direct method of assessing the potential role of secretory proteins, ovine pars tuberalis cells have been cultured and radiolabelled with 35S-methionine, and the accumulation of specific radioactive products in the medium, measured after separation by SDS-PAGE and fluorography. The synthesis and secretion of a number of labelled proteins are increased by forskolin (1 microM) and inhibited dose dependently by melatonin (IC50, 300 pM), although consistently a 72-kD protein (p72), is the most intensely labelled of these. Thus, 72 acts as a useful marker of cellular activity for melatonin, whereas prolactin (p23) provides a melatonin non-responsive marker in ovine pars tuberalis cell cultures. The synthesis and secretion of p72 and other melatonin-sensitive proteins is regulated through the cyclic AMP/protein kinase A second-messenger pathway, as analogues of cyclic AMP mimic the action of forskolin, yet 1,9-dideoxyforskolin, a forskolin analogue that is not active on adenylate cyclase, has no effect. However, the phorbol ester, phorbol-12,13-myristate acetate, also regulates the synthesis and secretion of the same profile of proteins as forskolin indicating a potential role for protein kinase C, which occurs through an independent rather than a synergistic pathway. The differential effects of nocadazole (1 microM) and extracellular calcium depletion upon p72 and prolactin secretion indicates that p72 is secreted by a calcium and microtubule independent pathway, in contrast to prolactin. These observations in conjunction with the absence of dense-core storage vesicles in melatonin-responsive cells of the ovine PT are consistent with constitutive secretion of p72 from the latter and regulated secretion of prolactin from melatonin non-responsive cells. Using immunoprecipitation de novo synthesis and secretion of either LH or LH-like proteins from ovine pars tuberalis cells could not be detected under the conditions used. The absence of 125I-(Des-Gly10[D-Ala6]-LHRH-ethylamide) binding over most, but not all, of the ovine pars tuberalis supports the contention that the majority of the cells of the ovine pars tuberalis are not gonadotrophs. These results provide further support for the unique function for the pars tuberalis.
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PMID:p72, a marker protein for melatonin action in ovine pars tuberalis cells: its regulation by protein kinase A and protein kinase C and differential secretion relative to prolactin. 820 12