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

The adenylate cyclase system has been implicated in taste transduction. The purpose of this study was to determine whether application of modulators of the adenylate cyclase system to the tongue alter taste responses. Integrated chorda tympani (CT) recordings were made in gerbils to bitter, sweet, salty, sour, and glutamate tastants before and after a 4-min application of four types of modulators of the adenylate cyclase system. The four types of modulators tested were: a) NaF, a compound that promotes dissociation of GTP binding protein; b) forskolin, a powerful stimulant of adenylate cyclase; c) 8-bromoadenosine 3' :5'-cyclic monophosphate sodium salt (8BrcAMP) and N6,2'-O-dibutyryl-adenosine 3' :5'-cyclic monophosphate sodium salt (DBcAMP), two membrane permeable forms of cAMP; and d) 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine dihydrochloride (H-7) and N-(2-[methylamino]ethyl)-5-isoquinolinesulfonamide dihydrochloride) (H-8), which are protein kinase inhibitors. The tast compounds tested were: NaCl (30 mM), monosodium glutamate-MSG (50 mM), sucrose (30 mM), HCl (5 mM and 10 mM), KCl (300 mM), quinine HCl (30 mM), MgCl2 (30 mM), erythromycin (0.7 mM and 1 mM), HCl (5 mM and 10 mM), and urea (2 M). The main findings were as follows. NaF (20 mM) significantly inhibited responses to bitter compounds up to 35% and enhanced the response to sucrose by 30%. NaCl (20 mM), used as a control for NaF, inhibited most responses up to 78% with no enhancement of sucrose as seen with NaF. 8BrcAMP (1.16 mM) reduced the responses to bitter-tasting quinine HCl, MgCl2, and erythromycin but not to urea.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Modulators of the adenylate cyclase system can alter electrophysiological taste responses in gerbil. 797 5

Incubation of calmodulin-dependent protein kinase II with Ca2+ and calmodulin resulted in a marked inactivation of the enzyme. Chelation of Ca2+ by EGTA or addition of calmodulin antagonists, W-7 or trifluoperazine, completely blocked this inactivation. The concentration required for the half-maximal inactivation, 127 microM, is three to four orders of magnitude higher than that for the half-maximal activation of the enzyme. The Ca2+/calmodulin-independent activity of the proteolytic fragment of the enzyme, whose calmodulin-binding site involved in the enzyme activation was deleted, was also decreased by incubation with Ca2+ and calmodulin. These results suggest that calmodulin-dependent protein kinase II possesses a second, low-affinity calmodulin-binding site, which is distinct from the calmodulin-binding site involved in the activation of the enzyme, and that the binding of calmodulin to the second binding site causes the inactivation of the enzyme. The inactivation by Ca2+/calmodulin was temperature-dependent. The addition of both 500 microM ADP and 10 mM MgCl2 markedly protected the enzyme against the inactivation, while such a marked protection was not observed after the addition of either of the two alone. The addition of 5 microM autocamtide-2, a synthetic substrate peptide containing the amino acid sequence of the autophosphorylation site (Thr286/Thr287 in alpha/beta, gamma, and delta isoforms) lying within the autoinhibitory domain, also protected the enzyme against the inactivation by Ca2+/calmodulin, while syntide-2, another synthetic substrate peptide corresponding to a phosphorylation site of glycogen synthase, did not protect it even at a concentration as high as 304 microM.
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PMID:Inactivation of Ca2+/calmodulin-dependent protein kinase II by Ca2+/calmodulin. 798 85

We determined the mechanisms by which beta-agonists increase sodium (Na+) currents across rat alveolar type II (ATII) cells grown in primary culture. When ATII cells were patched in the cell-attached mode using symmetrical Na+ solutions (150 mM Na(+)-glutamate), single-channel currents were observed for holding potentials between -80 and 30 mV (referenced to the pipette solution) with a single-channel conductance of 27 +/- 3 pS, a mean open time (tau 1) of 3.3 +/- 0.15 ms and an open probability (Po) of 0.36 +/- 0.06 (n = 7). Addition of 10 microM terbutaline into the bath increased tau 1 to 6.43 +/- 0.5 ms and Po to 0.62 +/- 0.06 (n = 7) without affecting channel conductance. Single-channel currents with a conductance of 25 +/- 2 pS were also recorded across ATII cells patched in the inside-out mode. Addition of 250 U/ml of protein kinase A (PKA), 1 mM ATP, and 5 mM MgCl2 in the bath solution (150 mM Na(+)-glutamate) increased the single channel tau 1 from 3.26 +/- 0.15 to 7.38 +/- 0.38 and Po from 0.41 +/- 0.06 to 0.72 +/- 0.07 (n = 6) without altering conductance. Addition of 1 microM amiloride or ethylisopropylamiloride (EIPA) in the pipette solution (150 mM Na(+)-glutamate) blocked single-channel activity almost completely. Ionic substitution experiments showed the relative permeability of Na+ to K+ and Na+ to Cl- to be 7:1 and 8:1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of low-amiloride-affinity sodium channels in alveolar type II cells. 804 48

The regulation of neutral cholesterol ester hydrolase activity by changes in its phosphorylation state was studied in rat liver microsomes. Treatment with cAMP-dependent protein kinase resulted in increased enzyme activity, which was further enhanced by the addition of cAMP and MgATP. Consistent activations were also achieved with MgCl2 and MgATP, the magnesium effect being abolished by ethylenediaminetetraacetic acid and adenosine triphosphate. Cholesterol ester hydrolase was activated twofold by free calcium and Ca2+/calmodulin; this latter effect was blocked by the chelator ethylene-glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid and the calmodulin antagonist trifluoperazine. The phosphatase inhibitors pyrophosphate and glycerophosphate led to marked and dose-dependent increases in esterase activity, whereas okadaic acid elicited no effect. Furthermore, pyrophosphate and okadaic acid did not change the increases in enzyme activity promoted by Ca2+, Ca2+/calmodulin, Mg2+ and MgATP. Cholesterol ester hydrolase was inactivated in a concentration-dependent manner by nonspecific alkaline phosphatases. In cAMP-dependent protein kinase/cAMP- or Ca2+/calmodulin-activated microsomes, a time-dependent loss of activation in cholesteryl oleate hydrolysis was caused by alkaline phosphatase. These findings suggest that microsomal cholesterol ester hydrolase is activated through cAMP and Ca2+/calmodulin phosphorylation, whereas enzyme deactivation is dependent on phosphatase action.
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PMID:Regulation of rat liver microsomal cholesterol ester hydrolase by reversible phosphorylation. 813 99

Using a human autoimmune CREST antiserum, we identified a 97-kDa polypeptide in Tetrahymena cilia at the plus ends of ciliary microtubules and mammalian kinetochores (Miller, J. M., Wang, W., Balczon, R., and Dentler, W. L. (1990) J. Cell Biol. 110, 703-714). In this study, we examined the interactions of the ciliary 97-kDa protein with microtubules assembled from purified bovine brain tubulin. The 97-kDa protein binds to microtubules and is released from them with 75 mM MgCl2, the same condition used to release it from ciliary microtubules. The 97-kDa protein-microtubule association can be disrupted by ATP and by adenosine 5'-O-(thio-triphosphate), and this ATP sensitivity requires a soluble factor in the crude 97-kDa protein fraction. Fractionation of the crude 97-kDa protein fractions by gel filtration chromatography or by sucrose gradient centrifugation causes the loss of the microtubule binding activity of the 97-kDa protein. Fractions containing a high molecular weight protein complex (molecular mass, approximately 1500-2000 kDa) from the column or gradient fractions can restore the microtubule binding ability of the 97-kDa protein. These results suggest that the 97-kDa protein is part of a high molecular weight protein complex and that the complex, not the 97-kDa protein alone, is required for the 97-kDa protein-microtubule association. The association of the 97-kDa protein with microtubules is sensitive to ATP, which suggests that the 97-kDa protein-microtubule interaction may be regulated by an ATPase(s) or protein kinase(s)/phosphatase(s).
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PMID:Reversible association of a 97-kDa protein complex found at the tips of ciliary microtubules with in vitro assembled microtubules. 822 41

Peripheral blood eosinophils from normal subjects and patients with atopic dermatitis were isolated on a Percoll gradient and incubated with [gamma 32P] ATP in the presence of Mg2+. After the reaction was stopped, SDS/PAGE was performed and autoradiography was used to determine the incorporation of 32P into the proteins in the eosinophils. Both normodense and hypodense eosinophils showed 32P incorporation into the proteins at the molecular weights of 65 kDa & 66.2 kDa. These reactions were dependent upon Mg2+ concentration, and maximal response was observed at concentrations of 2-6 mM MgCl2. 32P incorporation into the bands was dependent upon the reaction time and temperature, and maximal response was observed at 20 degrees C. 32P incorporation into the proteins was inhibited by Ca2+ in a dose-dependent manner. Cyclic GMP at concentrations of 5 x 10(-8) to 5 x 10(-6) M enhanced the 32P incorporation. These data suggest the possible presence of protein kinase in human peripheral blood eosinophils.
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PMID:[Possible presence of protein kinase in human peripheral blood eosinophils]. 825 Jul 35

Rainbow trout were used to investigate the hormonal regulation by glucagon and insulin of hepatic triacylglycerol (TG) lipase activation. Two purified preparations of the trout hepatic TG lipase enzyme, the 110,000-g preparation and the resuspended ammonium sulfate fraction (ASF), were activated up to 58% with (in mM) 0.5 ATP, 0.01 cAMP, 5 MgCl2, and exogenous protein kinase over control levels. ATP or cAMP alone had no effect on activation. Activation of the trout hepatic lipase was reversible; complete inactivation of the ASF was obtained within 3 h in the presence of exogenous phosphorylase phosphatase. Adenosine 3',5'-cyclic monophosphate (cAMP)/ATP-dependent 32P-phosphorylation of trout hepatic lipase was observed within 5 min of incubation with the cAMP/ATP-Mg2+ activation system and 25 microCi [32P]ATP. Hormonal modulation of trout hepatic lipase phosphorylation was studied in isolated hepatocytes. Hepatocytes were incubated with [32P]-monopotassium phosphate for 3 h, then exposed to mammalian glucagon (GLU). Within 5 min, increased lipolysis was accompanied by a 95% increase in phosphorylation of the enzyme. Mammalian insulin (INS) depressed GLU-stimulated phosphorylation by 56% and inhibited GLU-stimulated lipolysis. These results indicate that GLU and INS modulate lipolysis in trout liver by altering phosphorylation of the TG lipase enzyme.
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PMID:Glucagon and insulin regulate lipolysis in trout liver by altering phosphorylation of triacylglycerol lipase. 834 95

We previously found in single channel studies that ryanodine receptor (RyR) channel activity can be made insensitive to block by Mg2+ when terminal cisternae of sarcoplasmic reticulum, incorporated into planar bilayers, are treated with protein kinase A (PKA) or Ca2+/calmodulin dependent protein kinase type II (CamPK II), and then again made sensitive by treatment with protein phosphatases [Hain J. Nath S. Mayrleitner M. Fleischer S. Schindler H. (1994) Phosphorylation modulates the function of the calcium release channel of sarcoplasmic reticulum from skeletal muscle. Biophys. J., 67, 1823-1833]. In this study, modulation by protein kinases and phosphatases on net Ca2+ uptake by TC is presented. Phosphorylation of TC vesicles with PKA, CamPK II, or protein kinase C (PKC) reduced the calcium loading rate of TC vesicles 3-fold, 2.1-fold and 1.7-fold, respectively, measured in the presence of 1 mM MgCl2. There is no effect when AMP-PNP is substituted for ATP. Phosphorylation of the RyR was also measured by incorporation of [gamma-32P]-phosphate from ATP. A phosphorylation stoichiometry of 1.94 +/- 0.1 (32P/RyR) for PKA, 0.89 +/- 0.08 for CamPK II and 0.95 +/- 0.16 for PKC was obtained under these conditions. A study of the time dependence of phosphorylation with PKA and CamPK shows a direct correlation of reduction in calcium loading rate with increased phosphorylation of the ryanodine receptor. Treatment with protein phosphatase 1 enhanced the calcium loading rate again, after it was reduced by PKA phosphorylation. Investigation of the magnesium dependency shows that even at higher [Mg2+] (6 mM), PKA phosphorylated TC vesicles have a 2.3-fold reduced calcium loading rate indicating insensitivity to block by Mg2+.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Phosphorylation with protein kinases modulates calcium loading of terminal cisternae of sarcoplasmic reticulum from skeletal muscle. 852 60

We have previously shown that nucleotide species (adenosine triphosphate [ATP] or guanosine triphosphate [GTP]), [Cl-], and anion species determine the steady-state phosphorylation of apical membrane proteins within human airway epithelium in vitro. We found that a Cl(-)-regulated 37-kD protein (p37) principally phosphorylated with GTP but not ATP as substrate. Here we show that apical membranes from sheep tracheal epithelium also contain a Cl(-)-regulated 37-kD phosphoprotein (p37s) and characterize one of the kinases involved in the regulation of p37s. Analysis of phosphorylation of apical membrane proteins with gamma[32P]GTP in the presence of MgCl2 showed that two proteins circa 19 and 21 kD (p19s and p21s) were transiently phosphorylated before p37s. Renaturation of apical membrane proteins within polyacrylamide gels showed that p19s and p21s autophosphorylated with either gamma[32P]GTP or gamma[32P]ATP as substrates, suggesting that the two proteins were kinases. Immunoblotting and immunoprecipitation with a specific polyclonal antibody showed that p21s was a membrane-bound isoform of nucleoside diphosphate kinase (NDPK, EC 2.7.4.6), a protein kinase which catalyzes transfer of terminal phosphate from ATP to diphosphate nucleotides and is, among other functions, essential for cell secretion. Incubation of apical membrane proteins in the presence of gamma[32P]ATP and guanosine diphosphate (GDP) (but not GDPbetaS) resulted in enhancement of phosphorylation of p37s. Dephosphorylation of NDPK was stimulated by the addition of Mg2+, Mn2+, and Co2+ (but not Zn2+ or Ca2+). Our data show that ovine trachea is a good model for further characterization of the chloride-dependent cascade in airway epithelium.
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PMID:Nucleoside diphosphate kinase and Cl(-)-sensitive protein phosphorylation in apical membranes from ovine airway epithelium. 947 15

Glucagon and arginine vasopressin (AVP) enhance renal magnesium conservation through actions within the loop of Henle and the distal tubule. Studies were performed on an immortalized mouse distal convoluted tubule (MDCT) cell line to characterize the cellular actions of these hormones on Mg2+ transport in this segment of the distal tubule. Glucagon and AVP increased cellular cAMP concentrations by about fivefold above basal levels in normal and Mg(2+)-depleted cells. Intracellular free Mg2+ concentration ([Mg2+]i) was determined on single MDCT cells using microfluorescence with mag-fura 2. To assess Mg2+ uptake, MDCT cells were first Mg2+ depleted (0.22 +/- 0.01 mM) by culturing in Mg(2+)-free media for 16 h and then placed in 1.5 mM MgCl2, and the [Mg2+]i was determined. [Mg2+]i returned to basal levels, 0.53 +/- 0.02 mM, with a mean refill rate, d([Mg2+]i/dt, of 164 +/- 5 nM/s. Both glucagon and AVP stimulated Mg2+ uptake into MDCT cells, 196 +/- 11 and 189 +/- 6 nM/s, respectively, at concentrations of 3 x 10(-7) M and 10(-7) M, respectively. Enhanced Mg2+ uptake for each of the hormones was concentration dependent and inhibited by the channel blocker, nifedipine. Hormone stimulation of Mg2+ entry was not dependent on protein synthesis. 8-Bromo-cAMP, 10(-4) M, enhanced Mg2+ uptake (225 +/- 13 nM/s), whereas phorbol esters were without effect. Finally, protein kinase A inhibition prevented glucagon and AVP stimulation of Mg2+ uptake, supporting the notion that the cAMP pathway is important as expected in the hormone action. These studies demonstrate that glucagon and AVP stimulate Mg2+ uptake in MDCT cells and suggest that these hormones act to control magnesium conservation in the convoluted segment of the distal tubule.
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PMID:Glucagon and arginine vasopressin stimulate Mg2+ uptake in mouse distal convoluted tubule cells. 948 27


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