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

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have characterized the ANF-R2 receptor-mediated inhibition of adenylate cyclase with respect to its modulation by several regulators. ANF (99-126) inhibits adenylate cyclase activity only in the presence of guanine nucleotides. The maximal inhibition (approximately 45%) was observed in the presence of 10-30 microM GTP gamma S, and at higher concentrations, the inhibitory effect of ANF was completely abolished. ANF-mediated inhibition was not dependent on the presence of monovalent cations, however Na+ enhanced the degree of inhibition by about 60%, whereas K+ and Li+ suppressed the extent of inhibition by about 50%. On the other hand, divalent cation, such as Mn2+ decreased the degree of inhibition in a concentration dependent manner, with an apparent Ki of about 0.7 mM, and at 2 mM; the inhibition was completely abolished. In addition, proteolytic digestion of the membranes with trypsin (40 ng/ml) resulted in the attenuation of ANF-mediated inhibition of adenylate cyclase. Other membrane disrupting agents such as neuraminidase and phospholipase A2 treatments also inhibited completely, the ANF-mediated inhibition of enzyme activity. N-Ethylmaleimide (NEM), phorbol ester and Ca(2+)-phospholipid dependent protein kinase (C-kinase) which have been shown to interact with inhibitory guanine nucleotide regulating protein (Gi) also resulted in the attenuation of ANF-mediated inhibition of adenylate cyclase activity. These results indicate that in addition to the Gi, the phospholipids and glycoproteins may also play an important role in the expression of ANF-R2 receptor-mediated inhibition of adenylate cyclase.
...
PMID:Characterization of ANF-R2 receptor-mediated inhibition of adenylate cyclase. 132 94

Our previous studies implicated the involvement of protein kinase-A in the inhibitory effects of isoproterenol and relaxin on oxytocin-stimulated phosphoinositide turnover in rat myometrium. To understand the possible mechanisms involved, the properties and regulation of phospholipase-C (PLC) in purified myometrial plasma membranes from estrogen-primed rats were studied. The PLC activity measured with exogenous [3H]phosphatidylinositol 4,5-bisphosphate as substrate was Ca2+ dependent. The nonhydrolyzable GTP analog guanosine 5'-(3-O-thio)triphosphate stimulated PLC activity with a ED50 of 1.6 microM and shifted the calcium dependence curve to the left. Guanosine 5'-(3-O-thio)triphosphate-stimulated phosphatidylinositol 4,5-bisphosphate hydrolysis was inhibited by activation of endogenous and exogenous cAMP-dependent protein kinase (PKA). The effects of endogenous and exogenous PKA were significantly reversed by IP20, a potent synthetic peptide inhibitor of PKA. In the presence of [gamma-32Pi]ATP and exogenous PKA, 32Pi was incorporated in an IP20-sensitive manner into major bands at approximately 17,000, 20,000-24,000, 33,000, 38,000, 40,000-44,000, and other higher mol wt. These data indicate that one or more GTP-binding proteins mediate activation of membrane-bound PLC in rat myometrium. Phosphorylation of one or more membrane-associated proteins by PKA may regulate myometrial PLC activity and play a role in the inhibitory effects of isoproterenol and relaxin.
...
PMID:Protein kinase-A inhibits phospholipase-C activity and alters protein phosphorylation in rat myometrial plasma membranes. 132 60

Varicella-zoster virus (VZV) ORF 47 lies in the unique long region of the VZV genome. Sequence homology studies have demonstrated that gene 47 possessed conserved protein kinase motifs. In this study, we investigated the properties of the ORF 47 product. First, a rabbit antiserum was raised against a protein generated from the fusion of the most antigenic ORF 47 domain with Escherichia coli beta-galactosidase. The high-titer antiserum reacted specifically with ORF 47 polypeptides translated in vitro. When incubated with VZV-infected cell lysate, the antiserum immunoprecipitated a phosphoprotein of M(r) 54,000, a size comparable with the predicted molecular mass. The precipitated viral protein was phosphorylated in a protein kinase assay; subsequent phosphoamino acid analysis indicated that the phosphotransferase associated with the ORF 47 protein was a serine protein kinase. Synthesis of the ORF 47 product in VZV-infected cell culture increased in the first and second days and plateaued after the third day of infection. The protein kinase activity associated with VZV ORF 47 had several distinctive biochemical properties: (i) its phosphotransferase activity was enhanced more by manganese than by magnesium, (ii) it utilized both ATP and GTP as donors of phosphate, and (iii) it phosphorylated both acidic and basic substrates. In summary, this report lends support to the computer homology data which predicted that VZV ORF 47 would encode a serine protein kinase.
...
PMID:Serine protein kinase associated with varicella-zoster virus ORF 47. 132 39

Signal sequence receptor alpha (SSR alpha) and calnexin are major calcium-binding proteins of the endoplasmic reticulum (ER) which are implicated in chaperone functions. They were identified as major membrane substrates after in vitro phosphorylation of ER membranes with [gamma-32P]GTP (Wada, I., Rindress, D., Cameron, P. H., Ou, W. J., Doherty, J.-J., II, Louvard, D., Bell, A. W., Dignard, D., Thomas, D. Y., and Bergeron, J. J. M. (1991) J. Biol. Chem. 266, 19599-19610). Using purified SSR alpha and associated calnexin as substrates, we have attempted to identify the kinase(s) responsible for their phosphorylation. A salt extract from canine pancreatic ER membranes and cytosol possessed SSR alpha kinase activity which showed identical chromatographic behavior through phosphocellulose, DEAE-Sepharose, and hydroxylapatite purification protocols. Final purification was effected from the cytosol with three polypeptides of 38, 36, and 28 kDa detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. On the basis of primary sequence analysis of the three subunits of the purified kinase and the reconstitution of phosphorylation of SSR alpha and associated calnexin in heat-inactivated ER membranes by the addition of the purified kinase we conclude that the ER-associated kinase responsible for the GTP phosphorylation of SSR alpha and associated calnexin is casein kinase II.
...
PMID:Casein kinase II phosphorylation of signal sequence receptor alpha and the associated membrane chaperone calnexin. 133 Nov

The catalytic alpha subunit of casein kinase II contains the 11 conserved domains characteristic of all protein kinases. Domain II and VII are involved in nucleotide binding and phosphotransfer. Two residues of the alpha subunit, Val-66 (in domain II) and Trp-176 (in domain VII), were changed to Ala-66 and Phe-176, the residues present in more than 95% of the identified protein kinase sequences. These changes altered the selectivity of the alpha subunit for ATP and GTP. The Ala-66 mutant showed an increase in the Km value for GTP from 45 to 71 microM, while the Km value for ATP decreased from 13 to 9 microM. The Km value for ATP with the Phe-176 mutant showed a decrease from 13 to 7 microM. A double mutant of Ala-66/Phe-176 showed the combined effects, with a Km of 6 microM for ATP and 70 microM for GTP. Alteration of Trp-176 to Lys-176, an amino acid which is not present in the corresponding position of any known protein kinase, resulted in a lack of phosphotransferase activity. The mutations, Val-66 to Ala-66 and Trp-176 to Phe-176, also altered the interaction of the alpha subunit with the regulatory beta subunit. In contrast to the wild-type alpha subunit, which was stimulated 4-fold by addition of the beta subunit, the Ala-66 and Ala-66/Phe-176 mutants were not stimulated by the beta subunit, while the Phe-176 mutant was stimulated only 2.5-fold. All of the reconstituted holoenzymes were similar in molecular weight to the native holoenzyme. The stimulation of the phosphotransferase activity toward beta-casein B by spermine and polylysine, which is mediated by the beta subunit, was similar for holoenzymes reconstituted with either wild-type or mutant alpha subunits. Therefore, binding of the beta subunit appears to alter the active site of the alpha subunit directly or indirectly by inducing a conformational change. Ala-66 and Phe-176 mutations appear to change the structure of the alpha subunit sufficiently so that interaction of the subunits is altered and the stimulatory effect of the beta subunit is reduced or eliminated.
...
PMID:Characterization of the phosphotransferase domain of casein kinase II by site-directed mutagenesis and expression in Escherichia coli. 133 Nov 4

In the yeast Sacchromyces cerevisiae, addition of glucose to starved cells triggers a transient rise in the intracellular level of cyclic AMP that induces a protein phosphorylation cascade. The glucose signal is processed by the Cdc25/Ras/adenylyl cyclase pathway, where the role of Cdc25 is to catalyse the GDP-GTP exchange on Ras. The molecular mechanisms involved in the regulation of the activity of Cdc25 are unknown. We report here the use of highly selective anti-Cdc25 antibodies to demonstrate that Cdc25 is a phospho protein and that in response to glucose it is hyperphosphorylated, within seconds, by the cyclic AMP-dependent protein kinase. It is also demonstrated that, concomitantly with hyperphosphorylation, Cdc25 partially relocalizes to the cytoplasm, reducing its accessibility to membrane-bound Ras. These results are of general significance because of the highly conserved sequence of Ras-guanyl nucleotide exchange factors from yeasts to mammals.
...
PMID:Phosphorylation of the S. cerevisiae Cdc25 in response to glucose results in its dissociation from Ras. 133 34

1. Wide-tipped, low-resistance (approximately 1 M omega) pipettes were used to record the whole-cell Cl- current activated by cAMP-dependent protein kinase (PKA) in guinea-pig ventricular myocytes internally dialysed with or without GTP. Without GTP in the pipette, the response to 1 microM-isoprenaline declined with time and eventually disappeared, usually within approximately 20 min of rupturing the membrane and beginning cell dialysis. 2. This rundown of the isoprenaline response occurred more quickly with wider, lower-resistance pipette tips. 3. After complete rundown of the isoprenaline response, histamine (10 microM), another agonist known to elicit the Cl- current, also had no effect, but extracellular forskolin (1 microM) or intrapipette cAMP (1 mM) could still readily elicit the Cl- current. 4. In contrast, with 100 microM-GTP in the pipette, the response to 1 microM-isoprenaline was well maintained for periods greater than 20 min. But, if GTP was then withdrawn from the pipette, a rundown of the isoprenaline response was seen comparable to that in the experiments begun with GTP-free pipette solution. Moreover, in experiments begun without pipette GTP, the addition of 100 microM-GTP to the pipette solution, after the response to isoprenaline had disappeared, was able to restore that Cl- current response. 5. With GTP in the pipette, the forskolin-induced Cl- current could be suppressed by concurrent exposure to carbachol (10 microM). That inhibition was not seen in myocytes pretreated with pertussis toxin. In untreated myocytes dialysed with GTP-free pipette solution, after disappearance of the isoprenaline response, the muscarinic receptor-mediated inhibition was itself abolished. 6. We confirm that both beta-adrenoceptor-mediated activation of the Cl- current by isoprenaline, and muscarinic receptor-mediated inhibition of the forskolin-induced Cl- current, are mediated by G proteins, and conclude that the disappearance of both receptor-mediated responses during whole-cell recording with GTP-free pipette solution reflects the fall of cellular [GTP] below the level required to maintain G protein-dependent signal transduction.
...
PMID:Pipette GTP is essential for receptor-mediated regulation of Cl- current in dialysed myocytes from guinea-pig ventricle. 133 50

Recent studies have demonstrated that chronic stress increases the firing rate and expression of tyrosine hydroxylase (TH) in neurons of the locus coeruleus (LC), the major noradrenergic nucleus in brain. The present study was undertaken to examine the influence of chronic stress and other treatments known to influence the activity of LC neurons on the cyclic AMP (cAMP) second messenger system in these neurons. Chronic (5 days) cold exposure significantly increased levels of TH immunoreactivity in the LC, as previously reported, but not in substantia nigra (SN) or ventral tegmentum (VT), two dopaminergic nuclei studied for comparison. Chronic cold exposure increased levels of cAMP-dependent protein kinase activity in soluble, but not particulate, fractions of the LC, and increased basal and GTP- and forskolin-stimulated adenylate cyclase activity in this brain region. In contrast, levels of the protein kinase and adenylate cyclase in VT, SN, and frontal cortex were not significantly influenced by cold exposure. To study further the relationship between regulation of LC firing rate, TH expression, and the cAMP system in the LC, other treatments known to influence TH were examined. Reserpine treatment, shown previously to increase levels of TH, was found to increase both LC firing rate and levels of soluble cAMP-dependent protein kinase activity in the LC. 6-Hydroxydopamine, shown previously to increase levels of TH and firing rate of LC neurons, also increased soluble levels of protein kinase activity. Other treatments known to either increase (adrenalectomy) or decrease (chronic imipramine) levels of TH in the LC were also found to increase or decrease, respectively, levels of cAMP-dependent protein kinase activity in this brain region.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Coordinate regulation of the cyclic AMP system with firing rate and expression of tyrosine hydroxylase in the rat locus coeruleus: effects of chronic stress and drug treatments. 134 39

Products of the ras gene family, termed p21ras, are GTP-binding proteins that have been implicated in signal transduction via receptors encoding tyrosine kinase domains. Recent findings have defined a superfamily of hemopoietin receptors that includes receptors for a number of interleukins and colony-stimulating factors. The intracellular portions of these receptors show only restricted homologies, have no tyrosine kinase domain, and provide no clues to the mode of signal transduction. However, in most cases the factors stimulate tyrosine phosphorylation. We demonstrate here that ligand-induced activation of the interleukin (IL)-2, IL-3, IL-5, and granulocyte-macrophage colony-stimulating factor receptors resulted in activation of p21ras in various hemopoietic cell lines. The only cytokine tested that binds to a hemopoietin receptor and that did not activate p21ras was IL-4. Activation of p21ras was also observed in response to Steel factor, which stimulates the endogenous tyrosine kinase activity of the c-kit receptor, as well as with phorbol esters, which activate protein kinase C. Experiments with protein kinase inhibitors implicated tyrosine kinase activity, but not protein kinase C activity, as the upstream signal in p21ras activation via these growth factor receptors. Attempts to demonstrate tyrosine phosphorylation of the p21ras GTPase-activating protein (GAP) were negative, suggesting that phosphorylation of GAP may not be the major mechanism for regulation of p21ras activity by tyrosine kinases.
...
PMID:p21ras activation via hemopoietin receptors and c-kit requires tyrosine kinase activity but not tyrosine phosphorylation of p21ras GTPase-activating protein. 137 79

1. ATP activates calcium (Ca2+) influx in mouse lacrimal acinar cells in the absence of phosphoinositide hydrolysis. Extracellular ATP (1 mM) activates receptor-operated cation channels, promoting entry of Na+ and Ca2+ (inward current). This Ca2+ influx in turn activates K+ channels resulting in a delayed, outward, current component. The present study uses patch-clamp current recording techniques to investigate the role of beta-adrenoceptor mechanisms, intracellular cyclic AMP and GTP in the regulation of the ATP-induced inward currents. 2. The beta-adrenoceptor agonist, isoprenaline (1 microM), does not increase the resting membrane currents but markedly enhances the ATP-induced inward and outward currents. This effect of isoprenaline is blocked by the beta-adrenoceptor antagonist propranolol. 3. Internal application of cyclic AMP mimics the potentiating effect of isoprenaline. 100 microM-cyclic AMP increases the ATP-induced inward and outward currents to about 200% as compared to control responses. 4. Pre-treatment of the cells with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX; 1 mM), also results in a marked potentiation of the ATP-induced inward currents to 170% as compared to control responses. 5. The ATP-induced inward current responses are not blocked by either the removal of extracellular Ca2+ or by chelation of intracellular Ca2+ (by inclusion of 10 mM-EGTA in the recording pipette). Both protocols did however block the potentiating effect of internal cyclic AMP on the ATP-induced inward current responses. 6. Intracellular ATP (10 mM) reduces the amplitude of the inward currents evoked by external ATP application by about 60% and the currents were no longer potentiated by internal cyclic AMP. 7. Intracellular GTP or GTP-gamma-S (100 microM in the pipette solution) potentiates the current responses to ATP, increasing both the amplitude and duration of the inward currents. 8. In excised inside-out patches, with ATP in the recording pipette (i.e. external ATP), the catalytic subunit of the cyclic AMP-dependent protein kinase activated the cation channels. The effect of the catalytic subunit was readily reversible and abolished by an inhibitor of the protein kinase. 9. External ATP activates Ca2+ influx in lacrimal acinar cells by a mechanism that is distinct from that activated by phosphoinositide-coupled receptors. The effect is mediated by direct activation of cation channels in the cell surface membrane which allow for significant entry of Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:The ATP-induced inward current in mouse lacrimal acinar cells is potentiated by isoprenaline and GTP. 137 29


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---