Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acidification of the endosomal pathway is important for ligand and receptor sorting, toxin activation, and protein degradation by lysosomal acid hydrolases. Fluorescent probes and imaging methods were developed to measure pH to better than 0.2 U accuracy in individual endocytic vesicles in Swiss 3T3 fibroblasts. Endosomes were pulse labeled with transferrin (Tf), alpha 2-macroglobulin (alpha 2M), or dextran, each conjugated with tetramethylrhodamine and carboxyfluorescein (for pH 5-8) or dichlorocarboxyfluorescein (for pH 4-6); pH in individual labeled vesicles was measured by ratio imaging using a cooled CCD camera and novel image analysis software. Tf-labeled endosomes acidified to pH 6.2 +/- 0.1 with a t1/2 of 4 min at 37 degrees C, and remained small and near the cell periphery. Dextran- and alpha 2M-labeled endosomes acidified to pH 4.7 +/- 0.2, becoming larger and moving toward the nucleus over 30 min; approximately 15% of alpha 2M-labeled endosomes were strongly acidic (pH less than 5.5) at only 1 min after labeling. Replacement of external Cl by NO3 or isethionate strongly and reversibly inhibited acidification. Addition of ouabain (1 mM) at the time of labeling strongly enhanced acidification in the first 5 min; Tf-labeled endosomes acidified to pH 5.3 without a change in morphology. Activation of phospholipase C by vasopressin (50 nM) enhanced acidification of early endosomes; activation of protein kinase C by PMA (100 nM) enhanced acidification strongly, whereas elevation of intracellular Ca by A23187 (1 microM) had no effect on acidification. Activation of protein kinase A by CPT-cAMP (0.5 mM) or forskolin (50 microM) inhibited acidification. Lysosomal pH was not affected by ouabain or the protein kinase activators. These results establish a methodology for quantitative measurement of pH in individual endocytic vesicles, and demonstrate that acidification of endosomes labeled with Tf and alpha 2M (receptor-mediated endocytosis) and dextran (fluid-phase endocytosis) is sensitive to intracellular anion composition, Na/K pump inhibition, and multiple intracellular second messengers.
 ...
PMID:Second messengers regulate endosomal acidification in Swiss 3T3 fibroblasts. 138 79

The effect of auranofin (AF), retinoic acid (RA), and three heavy metals reacting with thiol groups (Hg, Cd, Pb) has been compared on a PKC mediated response of intact macrophages (i.e. plasminogen activator (PA) induction) and on purified PKC activity. AF, cadmium chloride, and lead nitrate directly inhibit PKC and hence prevent the induction of PA activity in macrophages stimulated with PMA. In vitro, and in absence of chelators, mercuric chloride is also a potent inhibitor of PKC. However, at the cellular level, the PKC mediated response (PA induction) was not inhibited by non-cytotoxic concentrations of mercury possibly due to interference of the metal with additional cellular mechanisms such as calcium mobilisation. Direct inhibition of PKC is probably not the mechanism by which retinoids block the activation of macrophages.
 ...
PMID:Comparison of the effects of auranofin, heavy metals and retinoids on protein kinase C in vitro and on a protein kinase C mediated response in macrophages. 225 79

Rat liver nuclei protein kinase C is identified as type II isozyme employing monospecific antibodies obtained against each three types of rat brain protein kinase C isozymes. (Yoshida, Y., Huang, F. L., Nakabayashi, H., and Huang, K-P. (1988) J. Biol. Chem. 263, 9868-9873). A major immunoreactive protein band at 80 kDa was revealed by type II isozyme antibodies at each step of purification, nuclear extract included. The nuclear protein kinase C has been purified to apparent homogeneity as revealed by silver nitrate staining on sodium dodecyl sulfate-polyacrylamide gel electrophoresis showing a single 80 kDa protein band. It does seem that 66 kDa protein (Masmoudi, A., Labourdette, G., Mersel, M., Huang, F. L., Huang, K.-P., Vincendon, G., and Malviya, A. N. (1989) J. Biol. Chem. 264, 1172-1179) is a major contaminant devoid of any protein kinase activity. The ratio obtained between protein kinase C enzymatic activity over phorbol dibutyrate bound, at various purification steps, indicates that the nuclear enzyme is a phorbol ester receptor. When isolated nuclei were incubated with 12-O-tetradecanoyl phorbol-13-acetate, endogenous protein kinase C activity was elevated about 8-10-fold suggesting the existence of phorbol ester signaling pathway at the level of nucleus. The role of nuclear protein kinase C is delineated in the regulation of inducible gene transcription
 ...
PMID:Rat liver nuclei protein kinase C is the isozyme type II. 230 97

K influx into resealed human red cell ghosts increases when the ghosts are swollen. The influx demonstrates properties similar to volume-sensitive K fluxes present in other cells. The influx is, for the most part, insensitive to the nature of the major intracellular cation and therefore is not a K-K exchange. The influx is much greater when the major anion is Cl than when the major anion is NO3; Cl stimulates the flux and, at constant Cl, NO3 inhibits it. Increase in the influx rate is rapid when shrunken ghosts are swollen or when NO3 is replaced by Cl. The volume-sensitive K influx requires intracellular MgATP at low concentrations, and ATP cannot be replaced by nonhydrolyzable ATP analogues. The volume-sensitive influx is inhibited by Mg2+ and by high concentrations of vanadate, but is stimulated by low concentrations of vanadate. It is not modified by cAMP, the removal of Ca2+ by EGTA, substances that activate protein kinase C, or by inhibition of phosphatidylinositol kinase. The influx is inhibited by neomycin and by trifluoperazine.
 ...
PMID:Volume-sensitive K influx in human red cell ghosts. 285 1

In the rat liver homogenate, maximal protein kinase C activity was found at two calcium concentrations (1.75 and 3.5 mM). Subcellular fractionation of the liver homogenate revealed that the protein kinase C activity requiring 1.75 mM calcium was present only in the cytosolic and particulate subcellular fractions. The protein kinase C activity requiring 3.5 mM calcium concentration was mainly located in the rat liver nuclei preparation. About 19% of the liver homogenate protein kinase C activity requiring 3.5 mM calcium was present in the nuclei. Goat anti-rat brain protein kinase C antibodies revealed a single immunoreactive band at 80-82 kDa in the rat liver nuclear, particulate, or cytosolic fractions. Based on the ratio of plasma membrane marker enzyme activity determined in the nuclear preparation, the purity of the isolated nuclei was ascertained. Rat liver nuclear protein kinase C activity has been partially purified. The purification steps sequentially employed were Triton X-100 extraction of isolated nuclei, DEAE-cellulose chromatography, Phenyl-Superose, and Mono Q (fast protein liquid) chromatography. The final purification step revealed, by silver nitrate staining on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two protein bands at 80 and 66 kDa, respectively. These findings provide definitive data regarding the nuclear location of protein kinase C. The nuclear location of protein kinase C may lead to an understanding of the molecular pathway involved in signal transduction from the plasma membrane to the nucleus.
 ...
PMID:Protein kinase C located in rat liver nuclei. Partial purification and biochemical and immunochemical characterization. 291 Aug 49

The phorbol ester TPA (12-O-tetradecanoylphorbol-13-acetate) stimulates baseline Na+ transport across frog skin epithelium and partially inhibits the natriferic response to vasopressin. The effects are produced largely or solely when TPA is added to the mucosal surface of the tissue. Although TPA activates protein kinase C, it has other effects, as well. Thus, the biochemical basis for the effects and the ionic events involved have been unclear. Furthermore, the physiologic implications have been obscure because of the sidedness of TPA's actions. We now report that two synthetic diacylglycerols (DAG) replicate the stimulatory and inhibitory effects of TPA on frog skin. DAG is the physiologic activator of PKC. In this tissue, it produces half-maximal stimulation at a concentration of less than or equal to 19 microM. In contrast to TPA, DAG is about equally effective from either tissue surface. In a series of eight experiments, DAG was found to depolarize the apical membrane. Diacylglycerol also increases the paracellular conductance of frog skins bathed with mucosal Cl- Ringer's solution. The latter effect can be minimized by replacing NO3- for Cl- in the mucosal solution. Under these conditions, combined intracellular and transepithelial measurements indicated that DAG increased both the apical Na+ permeability and intracellular Na+ concentration. These results are qualitatively similar to the effects of cyclic 3',5'-AMP on this tissue, suggesting that activation of PKC by DAG causes phosphorylation of the same or nearby gating sites phosphorylated by cAMP. We propose that apical Na+ entry is regulated in part by activation of PKC, and that insulin may be a physiologic trigger of this activation.
 ...
PMID:Diacylglycerols stimulate short-circuit current across frog skin by increasing apical Na+ permeability. 349 45

We sought to examine mechanisms responsible for increased vasoconstriction that occurs during development of nitroglycerin tolerance. Rabbits were treated for 3 days with nitroglycerin patches (0.4 mg/hr), and their aortic segments were studied in organ chambers. This treatment resulted in attenuated in vitro relaxations to nitroglycerin and increased contractile sensitivity to angiotensin II, serotonin, phenylephrine, KCl, and a direct activator of protein kinase C, the phorbol ester phorbol 12,13-dibutyrate. The protein kinase C antagonists calphostin C (100 nM) and staurosporine (10 nM) corrected the hypersensitivity to constrictors in tolerant vessels, yet had minimal effects on constrictions in control vessels. Paradoxically, constrictions caused by endothelin 1 were decreased in nitrate-tolerant vessels. Immunocytochemical analysis revealed intense endothelin 1-like and big endothelin 1-like immunoreactivity in the media of nitroglycerin-tolerant but not of control aortas. The enhanced vasoconstriction to angiotensin II, serotonin, KCl, and phenylephrine could be mimicked in normal vessels by addition of subthreshold concentrations of endothelin 1, and this effect was prevented by calphostin C. We propose that increased autocrine production of endothelin 1 in nitrate tolerance sensitizes vascular smooth muscle to a variety of vasoconstrictors through a protein kinase C-mediated mechanism.
 ...
PMID:Evidence for a role of endothelin 1 and protein kinase C in nitroglycerin tolerance. 753 47

We have explored the possible involvement of the phosphoinositide (PI) cycle and protein kinase C (PKC) in the phytochrome (Pfr)-mediated light signal transduction pathway using nitrate reductase (NR) and phytochrome-I (PhyI) genes as model systems. We have shown earlier that phorbol myristate acetate (PMA) completely replaces the red light effect in stimulating nitrate reductase activity and transcript levels in maize. In this paper, we present detailed evidence to show that PMA mimics the red light effect and follows similar kinetics to enhance NR steady-state transcript accumulation in a nitrate-dependent manner. We also show that PMA inhibits phyI steady-state transcript accumulation in a manner similar to red light, indicating that a PKC-type enzyme(s) may be involved in mediating the light effect in both cases. Serotonin or 5-hydroxytryptamine (5-HT), a stimulator of PI turnover, was also found to mimic the red light effect in enhancing NR transcript levels and inhibiting phyI transcript accumulation, indicating the role of the PI cycle in generating second messengers for regulating the two genes. These results indicate that phytochrome-mediated light regulation of NR and phyI gene expression may involve certain common steps in the signal transduction pathway such as the PI cycle and protein phosphorylation by a PKC-type enzyme.
 ...
PMID:Evidence for some common signal transduction events for opposite regulation of nitrate reductase and phytochrome-I gene expression by light. 757 65

To elucidate whether cytokines induce nitric oxide synthase in vascular smooth muscle cells, we studied the effects of human recombinant interleukin-1 beta on the synthesis and release of nitric oxide in cultured rat vascular smooth muscle cells by measurement of NO2-/NO3- levels. Furthermore, we performed Northern blot analysis using subcloned polymerase chain reaction products as probes for constitutive and inducible nitric oxide synthase. Interleukin-1 beta dose dependently (1 to 20 ng/mL) stimulated NO2-/NO3- production as a function of time. Northern blotting demonstrated the interleukin-1 beta-induced expression of messenger RNA for an inducible but not for the constitutive nitric oxide synthase after 3 hours. NG-Monomethyl L-arginine completely blocked the interleukin-1 beta-induced NO2-/NO3- production, the effect of which was reversed by L-arginine but not by D-arginine. Dexamethasone inhibited the interleukin-1 beta-induced NO2-/NO3- production in a dose-dependent manner (10(-9) to 10(-7) M) and the interleukin-1 beta-inducible nitric oxide synthase messenger RNA levels. Neither a calmodulin inhibitor (W-7) nor a protein kinase C inhibitor (staurosporine) showed any effects on the induction of nitric oxide synthase transcripts or production of NO2-/NO3- stimulated by interleukin-1 beta, whereas cycloheximide and actinomycin D completely inhibited the basal and stimulated NO2-/NO3- production. These data demonstrate for the first time that interleukin-1 beta induces gene expression of inducible nitric oxide synthase and its de novo protein synthesis in rat vascular smooth muscle cells, thereby leading to generation of nitric oxide via Ca2+/calmodulin-independent and protein kinase C-independent mechanisms.
 ...
PMID:Induction of nitric oxide synthase gene by interleukin in vascular smooth muscle cells. 768 32

cDNA encoding a Cl- channel was isolated from a rabbit gastric library, sequenced, and expressed in Xenopus oocytes. The predicted protein (898 amino acids, relative molecular mass 98,433 Da) was overall 93% similar to the rat brain ClC-2 Cl- channel. However, a 151-amino acid stretch toward the COOH-terminus was 74% similar to ClC-2 with six amino acids deleted. Two new potential protein kinase A (PKA) phosphorylation sites (also protein kinase C phosphorylation sites) were introduced. cRNA-injected Xenopus oocytes expressed a Cl- channel that was active at pHtrans 3 and had a linear current-voltage (I-V) curve and a slope conductance of 29 +/- 1 pS at 800 mM CsCl. A fivefold Cl- gradient caused a rightward shift in the I-V curve with a reversal potential of +30 +/- 3 mV, indicating anion selectivity. The selectivity was I- > Cl- > NO3-. The native and recombinant Cl- channel were both activated in vitro by PKA catalytic subunit and ATP. The electrophysiological and regulatory properties of the cloned and the native channel were similar. The cloned protein may be the Cl- channel involved in gastric HCl secretion.
 ...
PMID:Cloning, functional expression, and characterization of a PKA-activated gastric Cl- channel. 784 Jan 47


1 2 3 4 5 6 7 Next >>