排序方式: 共有18条查询结果,搜索用时 15 毫秒
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Rac is an activating factor for Nox1, an O2−-generating NADPH oxidase, expressed in the colon and other tissues. Rac requires a GDP-GTP exchange factor for activation. Nox1 activation by βPix has been demonstrated in cell lines. We examined the effects of βPix and its phosphomimetic mutant on endogenous Nox1 in Caco-2 cells transfected with Noxo1 and Noxa1. βPix expression enhanced O2− production in resting cells and cells stimulated with EGF or phorbol ester. βPix(S340E) further enhanced O2− production, while βPix(S340A) eliminated the βPix effect. βPix(S340E), but not βPix(S340A), had higher affinity and GEF activity for Rac than wild-type βPix. These results suggest that βPix phosphorylation at Ser-340 upregulates Nox1 through Rac activation, confirming Rac as a trigger for acute Nox1-dependent ROS production. 相似文献
13.
Melanie Schwarten Carsten Berghaus Rolf Heumann Raphael Stoll 《Biomolecular NMR assignments》2007,1(1):105-108
Ras homologue enriched in brain (Rheb) is a small GTPase that plays an important role in tuberous sclerosis. Here we present
the backbone assignments of activated rRheb in complex with the non-hydrolisable GTP analogue GppNHp. These assignments now
provide a basis for the analysis of rRheb’s interaction with putative effectors in order to further elucidate the physiological
function of this GTPase and its role in the regulation of neuronal cell volume as well as in tuberous sclerosis. 相似文献
14.
Formation of a Persistent Inhibitory State of Brain Adenylate Cyclase by GTP Analogs 总被引:4,自引:3,他引:1
Addition of 10 microM guanyl-5'-ylimidodiphosphate at 30 degrees or 0 degree to guinea pig brain particulates instantaneously evoked nearly 50% inhibition of adenylate cyclase activity as determined after removal of the GTP analog by washing of the particulates. The inhibitory state, once formed, persisted for at least 60 min as long as the preparation was kept either in a medium devoid of the analog (0-30 degrees) or in its presence at 0 degree. During incubation at 30 degrees in the presence of the analog, however, the inhibited or nontreated enzyme showed a gradual increase in enzyme activity. Both the inhibitory and the activating effects of the analog were saturable, with a half-maximal concentration of about 1.0 microM, and were antagonized by simultaneous addition of GTP, GDP, and GMP (in decreasing order). The persistently inhibited enzyme enabled the detection of marked stimulation by norepinephrine and histamine, whereas these amines showed only marginal stimulation of the enzyme before treatment with the analog. Formation of such a persistent inhibitory state appears to be specific to brain cyclase. 相似文献
15.
Joan M. Mansour Alan Ehrlich Tag E. Mansour 《Biochemical and biophysical research communications》1983,112(3):911-918
The liver fluke, , has a very active adenylate cyclase which can be stimulated by NaF or by serotonin and guanine nucleotides. Micromolar amounts of AlCl3 augment the activation by F-. In contrast, when the enzyme is activated with serotonin and guanine nucleotides, AlCl3 inhibits the activation. Aluminum also inhibits the activation by forskolin. Gallium mimics the effects of aluminum. 相似文献
16.
Adenylate cyclase in membrane fractions of RIN-A2-cells: studies with forskolin, NaF, GppNHp and NEM
In crude membrane fractions of rat pancreatic islets and of RIN-A2-cells, forskolin and NaF stimulated adenylate cyclase activity. Basal and stimulated enzyme activity was approximately 3 to 6 fold higher in membranes of RIN-A2-cells than in membranes of islet cells. In RIN-A2-cells GppNHp and NEM inhibited forskolin-stimulated enzyme activity. The inhibitory effect of GppNHp could be reduced by NEM. It is suggested that the adenylate cyclase system of RIN-A2-cells contains inhibitory and stimulatory N-proteins and that there are critical thiols related to Ni, Ns and/or the catalytic unit. Thus, membrane fractions of RIN-A2-cells may be an appropriate model for studies on the adenylate cyclase system of insulin-producing cells. 相似文献
17.
Carl L. Johnson Harel Weinstein Jack Peter Green 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,587(2):155-168
In particular preparations from guinea-pig ventricle, histamine in the concentration range 10?6–10?3 M caused a 3–5-fold stimulation of adenylate cyclase activity which was dependent on the presence of GTP. The effects of fourteen analogs of histamine were examined on this cyclase preparation. Five of the compounds studied proved to be partial agonists relative to histamine while nine others had essentially the same intrinsic activity as histamine. The intrinsic activities of the partial agonists were increased by GppNHP to the extent that dimaprit, which was a partial agonist in the presence of GTP, became a full agonist in the presence of GppNHp. The relative potencies of the full agonists as activators of the cyclase were found to correlate with the relative potencies on physiologically defined H2 receptor systems. Activation of the cyclase by histamine, as well as by several of the agonist analogs, including dimaprit and tolazoline, was completely blocked by the H2 antagonist cimetidine, but was not affected by pharmacologically relevant concentrations of the H1 antagonist mepyramine, the β-blocker alprenolol, or the α-blocker phentolamine. The results suggest that all the agonists studied probably interact with a common H2 receptor site on the cardiac muscle cell leading to activation of adenylate cyclase. The accompanying increase in cyclic AMP is presumably responsible for the chronotropic and inotropic effects of histamine and related compounds on cardiac muscle. 相似文献
18.
S. Adamo M. Conti R. Geremia V. Monesi 《Biochemical and biophysical research communications》1980,97(2):607-613
Germ cells from the mouse testis possess both a particulate and a soluble form of adenylate cyclase (EC 4.6.1.1). Germ cell adenylate cyclase activity is Mn++ dependent and is not stimulable with either NaF or 5′guanylylimidodiphosphate. Both particulate and soluble adenylate cyclase specific activities increase as germ cells progress through their differentiative stages, but epididymal spermatozoa seem to lack a significant amount of soluble activity. Somatic cells of the seminiferous tubule possess only a membrane bound activity, which is Mg++ and Mn++ dependent, NaF and 5′guanylylimidodiphosphate stimulable. It is suggested that germ cell adenylate cyclases represent incomplete forms of the enzyme, devoid of regulative subunits. 相似文献