Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.2 (guanylate cyclase)
 8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Atrial natriuretic peptide (ANP) has been shown to affect water and ion transport and specific ANP binding has been identified in several secretory tissues. ANP commonly acts via stimulation of membrane-bound particulate guanylate cyclase with the production of cyclic guanosine monophosphate (cGMP). We questioned whether ANP played a role in the complex cyclic transformation of the endometrium into a secretory tissue, and whether its action was cGMP mediated. Endometrium was obtained by biopsy in regularly menstruating women and stromal cells were isolated and cultured for use in this study. ANP competitive binding assays were performed using 125I-labeled ANP (0.1 nmol/L) and increasing concentrations of unlabeled ANP (0-1000 nmol/L). Optimal binding was obtained after 3-h incubation at 4 C and binding characteristics, including dissociation constant and binding site quantity, were estimated by Scatchard analysis. Specific, high affinity (dissociation constant, 0.078 +/- 0.004 nmol/L) and low capacity (4,877 +/- 1,951 binding sites/cell) ANP binding was identified, with nonspecific binding representing less than or equal to 16% of total binding. Evaluation of ANP-stimulated cyclic nucleotide production revealed an increase in cGMP production, with a 7-fold increase at 1000 nmol/L ANP, and no effect on cAMP production. In conclusion, we have identified specific high affinity receptors for ANP in human endometrial cells, suggesting a role for ANP in endometrial cell function and/or development mediated via cGMP production. We propose that ANP may affect local salt and water metabolism, may be involved in the secretory evolution of glandular and stromal cells, and may further facilitate endometrial development via modulation of local vascular tone and endothelial permeability.
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PMID:Atrial natriuretic peptide receptors in human endometrial stromal cells. 132 28

Guanylate cyclase from 105,000 X g particulate fractions of rat liver homogenates (20 pmoles of cyclic GMP formed/min/mg protein) was solubilized in the absence of detergents by incubating fractions 12 min at 37 degrees with 5 ug/ml trypsin. Optimal solubilization was dependent upon trypsin and particulate preparation concentrations. Virtually no activation of particulate guanylate cyclase was observed at any time point or trypsin concentration tested. Guanylate cyclase solubilized with trypsin was purified about 500-fold (9.4 nmoles/min/mg protein) using ammonium sulfate precipitation, GTP-affinity chromatography, and preparative polyacrylamide gel electrophoresis. Activity eluted as a single peak on Sepadex G-200 (Stokes radius = 40 A) and migrated as a single peak on sucrose density gradients (S20,w = 4.6). Thus, the tryptic fragment was estimated to be about 80,000 daltons (Mr) with a frictional ratio (f/fo) of 1.4. These partially purified preparations exhibited linear double reciprocal plots with Mn-GTP and Hill coefficients of 1.0. This is in contrast to the crude membrane-associated enzyme which had a Hill co-efficient of 1.5. Membrane-bound and trypsin-solubilized guanylate cyclase were activated 3- and 4-fold with nitric oxide and were inhibited with 1mM cystamine. Cystamine inhibition could be partially reversed with 7.5 mM dithiothreitol. These studies indicate that particulate guanylate cyclase solubilized by limited proteolysis is amenable to purification by "classical" chromatographic techniques. The partially purified fragment contains the catalytic site, the site for nitric oxide activation, and at least one sulfhydryl group required for activity.
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PMID:Partial purification and characterization of particulate guanylate cyclase from rat liver after solubilization with trypsin. 613 35

In the previous communication we described a histochemical method for measuring soluble guanylate cyclase (sGC) activity in sections of rat liver. In theory, this method could be used to assess nitric oxide synthase (NOS) activity by the increased sGC activity induced by the additional presence of the substrates for NOS activity. We found that this was correct provided that the concentration of the colloid stabilizer in the reaction medium was decreased to just below the concentration required to fully stabilize the guanylate cyclase activity in the sections. This was related to the fact that the site of NOS activity was different from that of the sGC activity in the hepatocytes, so that the NO generated had to diffuse from the Kupffer cells to the hepatocytes as could occur only in partially unstabilized sections. Optimal concentrations of arginine and of NADPH have been determined for demonstrating NOS activity; the increased reaction was shown to be largely inhibited by methyl-arginine.
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PMID:Measurement of nitric oxide synthase activity in sections of rat liver. 853 39

Second-messenger systems are involved in the regulation of numerous cellular processes. Adenylate cyclase (AC) and guanylate cyclase (GC) enzymes are in key positions in the regulation of these systems. The cerium method has been successfully applied to demonstrate amine- and neuropeptide-stimulated AC in rat nervous and adipose tissues and human sweat glands at the electron microscopic level. AC was also localized in cultured neurons. Nitric oxide compounds stimulated GC were demonstrated in rat hippocampal areas. Enzyme reactions were located in neurons pre- and postsynaptically in synapses; in addition, GC activity was seen intraneuronally and in glial cells. Adipocytes and eccrine glandular cells exhibited reaction products in their plasmalemmas. Optimal histochemical conditions are described, combined with control experiments. Some handicaps, related to the sensitivity of the enzymes to the fixatives, penetration problems of cerium salts, and especially the specificity of the method in phosphatase enzyme histochemistry in general are discussed.
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PMID:Cerium ions in the histochemical demonstration of second-messenger enzymes. 955 24