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

Soluble extracts prepared from quiescent Swiss mouse 3T3 cells that had been briefly exposed to various mitogens exhibited a 2- to 3-fold elevation in phosphorylating activities toward ribosomal protein S6 and a synthetic peptide, Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala (RRLSSLRA), patterned after a phosphorylation site sequence from S6. Optimal activation of the phosphorylating activity occurred within 15-20 min of exposure of the cells to platelet-derived growth factor (10 ng/ml), epidermal growth factor (100 nM), and insulin (100 nM), and 2-5 min after 12-O-tetradecanoylphorbol-13-acetate (TPA) (100 nM) treatment. Fractionation of the cytosolic extracts from mitogen- or TPA-treated cells on Sephacryl S-300, TSK-400, and DEAE-Sephacel columns gave results suggesting that a single stimulated kinase accounted for the enhanced S6 and RRLSSLRA phosphorylating activities. The mitogen-activated kinase had an apparent Mr of about 85,000 as determined with Sephacryl S-300, but eluted with an apparent Mr of 26,000 from a TSK-400 high pressure liquid chromatography column. The S6 kinase was also stimulated in cytosols from insulin-like growth factor 1- (100 nM), vasopressin- (250 nM), prostaglandin F2 alpha- (250 nM), and 10% fetal calf serum-treated cells but not from quiescent cells exposed to beta-transforming growth factor (2 ng/ml). TPA, vasopressin and prostaglandin F2 alpha appeared to stimulate this kinase via a protein kinase C-dependent mechanism, since the responses to these hormones, but not to platelet-derived growth factor, epidermal growth factor, and insulin, were lost in protein kinase C-depleted cells.
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PMID:Mitogen-activated S6 kinase is stimulated via protein kinase C-dependent and independent pathways in Swiss 3T3 cells. 330 94

The mechanisms by which platelet-activating factor (PAF) and thrombin increase intracellular calcium were examined. Platelets were loaded with the calcium-sensitive fluorescent probe Quin 2 and then were suspended in buffer containing 0.5 mM-Mn2+ in order to quantify simultaneously calcium release from intracellular stores and divalent cation influx. Pretreating platelets with agents which activate protein kinase C [the phorbol ester phorbol myristate acetate (PMA) or the diacylglycerol 1-oleoyl-2-acetylglycerol (OAG)] inhibited increased intracellular calcium by PAF and thrombin in a dose-related manner. That protein kinase C regulates intracellular calcium by phosphorylating proteins in two distinct pathways was suggested by two observations. PAF-induced calcium release was more sensitive to inhibition by PMA and OAG than was manganese influx and the kinetics of recovery from inhibition were different for the two pathways. Both PMA and OAG aggregated Quin 2-loaded platelets without eliciting measurable increases in intracellular calcium. In contrast, prostacyclin, which increases intracellular cyclic AMP, inhibited calcium release and influx in parallel, suggesting that this agent acts at a step common to both pathways.
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PMID:Modulation of platelet-activating-factor-induced calcium influx and intracellular calcium release in platelets by phorbol esters. 332 69

Confluent, nongrowing renal epithelial cells, LLC-PK1, have a low rate of Na+-dependent (A-system) amino acid transport. Following a brief period of amino acid and serum deprivation, but with glucose provided as an energy source, such cells respond to the tumor promoter TPA with a brief enhancement of A-system activity that returns to control levels within 10-20 min. The response is followed some 30 min later by a large and prolonged elevation of transport activity (delayed response). The responses may be related to an increased amino acid requirement in mitogenized cells. The initial transport response appears to be the consequence of a protein kinase C-dependent phosphorylation event, phosphorylating either a regulator or the transporter itself, while the delayed response is dependent on the synthesis of new protein. The delayed transport response may also be dependent upon an early phosphorylation event, although apparently less directly than the early transport response. Several candidate proteins that might be involved in the regulation of the response(s) may be seen when electrophoretically separated cell proteins are examined for 32P or [35S]methionine incorporation after TPA treatment.
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PMID:Biphasic response of Na+-dependent amino acid transport to tumor promoting phorbol esters in cultured renal epithelial cells, LLC-PK1. 338 Aug 19

cAMP-dependent protein kinase, protein kinase C, cGMP-dependent protein kinase, smooth muscle myosin light-chain kinase, and phosphorylase kinase were examined with respect to their ability to phosphorylate porcine atrial muscarinic receptors (mAcChRs). Experiments were performed both in detergent solution and in a reconstituted system containing the mAcChR alone or in the presence of the purified porcine atrial inhibitor guanine nucleotide binding protein (Gi). Only cAMP-dependent protein kinase was capable of phosphorylating the receptor under any of the experimental conditions examined. Phosphorylation of the mAcChR in the detergent-solubilized state resulted in a loss of ligand binding sites that was reversible upon treatment with calcineurin in the presence of calcium and calmodulin. Upon reconstitution, the apparent stoichiometry of phosphorylation was increased by about 15-fold. Carbachol-stimulated covalent incorporation of phosphate was found only in the reconstituted system in the presence of Gi, suggesting that the large agonist-stimulated increase in phosphorylation observed in vivo [Kwatra, M. M., & Hosey, M. M. (1986) J. Biol. Chem. 261, 12429-12432] may in part result from a unique receptor conformation that occurs upon association with this protein. Ligand binding studies indicated that phosphorylation of the mAcChR in the detergent-solubilized or reconstituted state did not affect its interaction with carbachol or L-quinuclidinyl benzilate in vitro. Carbachol-induced stimulation of the GTPase activity of Gi in the reconstituted system was also unaffected by phosphorylation.
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PMID:Phosphorylation of the porcine atrial muscarinic acetylcholine receptor by cyclic AMP dependent protein kinase. 344 51

Interleukin 3 (IL-3) promotes the survival, proliferation and development of progenitor cells from several distinct haemopoietic lineages and can also stimulate the self-renewal of stem cells. We have explored the mode of action of this growth factor in promoting survival and proliferation, using a multipotent haemopoietic stem cell line FDC-Mix 1. In the absence of IL-3 these cells died within 16-48 h. However, this requirement for IL-3 could be replaced by 12-O-tetradecanoylphorbol-13-acetate (TPA) plus Ca2+ ionophore, which promoted not only survival but also DNA synthesis with no concomitant loss of the multipotential nature of these cells. TPA and Ca2+ ionophore, respectively, could also interact synergistically with IL-3 to promote DNA synthesis. Both IL-3 and TPA stimulated the translocation of protein kinase C (PK-C) from the cytosol to a membrane-bound form in FDC-Mix 1 cells. Previously we suggested that IL-3 can activate the primary metabolism of IL-3-dependent cells so that increased glucose transport and glycolysis lead to maintenance of ATP levels and cellular survival. To investigate whether TPA and, or, Ca2+ ionophore could also influence cellular survival via an activation of glucose uptake we assessed the effects of these agents on hexose transport. TPA +/- Ca2+ ionophore activated hexose transport to the same degree as does IL-3 but these agents cannot superstimulate FDC-Mix 1 hexose transport in cells that already exhibit an activated transport system from preincubation with IL-3. We conclude that IL-3 maintains FDC-Mix 1 cells via its ability to activate PK-C and increase cytosolic levels of Ca2+, and that an IL-3-mediated activation of PK-C may promote cellular survival via its ability to enhance hexose uptake by phosphorylating the glucose transport protein.
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PMID:Phorbol esters activate protein kinase C and glucose transport and can replace the requirement for growth factor in interleukin-3-dependent multipotent stem cells. 349 4

Interleukin 2 (IL-2) and the synthetic diacylglycerol, 1-oleoyl-2-acetylglycerol (OAG), a direct activator of protein kinase C, induce phosphorylation of the ribosomal S6 protein in a murine IL-2-dependent lymphocyte clone. The phosphorylation of S6 protein was correlated with increased protein synthesis in this cell line. Using cell-free assay systems, two unique kinases capable of phosphorylating the S6 protein were identified, namely, a calcium/phospholipid-dependent phosphotransferase, protein kinase C, and a second phospholipid-independent kinase detected in crude cytosolic fractions. Peptide mapping of the S6 protein demonstrated that the degree of S6 phosphorylation stimulated by IL-2 and OAG was similar to that achieved using the second (calcium/phospholipid-independent) kinase but not to the level of phosphorylation achieved with protein kinase C. The kinase responsible for phosphorylating S6 was soluble in stimulated cells and was induced in a time-dependent manner by either IL-2 or diacylglycerol treatment of intact cells. These data support the notion that, although protein kinase C is activated by IL-2 or OAG, subsequent events such as S6 phosphorylation may be the result of the activation of secondary phosphotransferase systems regulated by protein kinase C.
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PMID:Interleukin 2 and diacylglycerol stimulate phosphorylation of 40 S ribosomal S6 protein. Correlation with increased protein synthesis and S6 kinase activation. 349 10

We have developed a cell-free assay to detect and characterize nerve growth factor (NGF)-activated protein kinase activity. Cultured PC12 cells were briefly exposed to NGF, and extracts of these were assayed for phosphorylating activity using exogenously added tyrosine hydroxylase as substrate. Tyrosine hydroxylase was employed since it is an endogenous substrate of NGF-regulated kinase activity and is activated by phosphorylation. In the cell-free assay, extracts prepared from NGF-treated cells yielded a 2-3-fold greater incorporation of phosphate into tyrosine hydroxylase as compared with extracts of control, NGF-untreated cells. Activation did not occur, however, if NGF was added directly to cell extracts. The NGF-stimulated phosphorylating activity appeared to be due to regulation of a protein kinase rather than of a phosphoprotein phosphatase. Characterization of the kinase (designated as kinase N) showed that it is soluble, is detectably activated within 1-3 min after cells are exposed to NGF and maximally activated by 10 min, is half-maximally activated with 0.5 nM NGF and maximally activated with 1 nM NGF, is detectable in the presence of either Mg2+ or Mn2+ but does not require Ca2+, does not require nonmacromolecular cofactors, can use histone H1 as a substrate, and exhibits a 2-fold increase in apparent Vmax in response to NGF but does not undergo a significant change in apparent Km for either ATP or GTP. A number of characteristics of kinase N were assessed including susceptibility to inhibitors, substrate specificity, cofactor requirements, ATP dependence, and lack of down-regulation by prolonged expose to a phorbol ester. These studies indicated that it lacks tyrosine kinase activity and is distinct from a variety of well-characterized protein kinases including cAMP-dependent protein kinase, protein kinase C (Ca2+/phospholipid-dependent enzyme), Ca2+/calmodulin-dependent kinase, and casein kinase II. Preliminary purification data show that the kinase has a basic pI and that it has an apparent Mr of 22,000-25,000. The only amino acid in tyrosine hydroxylase found to be phosphorylated by the semipurified kinase is serine.
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PMID:Cell-free detection and characterization of a novel nerve growth factor-activated protein kinase in PC12 cells. 358 24

A calcium-independent but 12-O-tetradecanoylphorbol-13-acetate (TPA)- or diacylglycerol-activated phospholipid-dependent phosphorylating activity has been separated from protein kinase C. This has been made possible by employing calcium-dependent hydrophobic interaction chromatography. The material bound to phenyl-Sepharose in the presence of calcium at low ionic strength was eluted with EGTA and was protein kinase C. While the unbound material passing through the phenyl-Sepharose column showed no appreciable protein kinase C activity, instead it had a high phosphorylating activity manifested in the absence of calcium and in the presence of TPA plus phospholipid. The identification of this phosphorylating activity, distinct from protein kinase C, leads to important clues to cellular responses monitored by TPA in the absence of calcium.
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PMID:Separation from protein kinase C--a calcium-independent TPA-activated phosphorylating system. 369 53

A procedure was devised to determine whether in the stimulated chromaffin cell phosphate is incorporated into specific proteins ("chromobindins") that bind to chromaffin granule membranes in a Ca2+-dependent manner. Cells were preincubated with 32P-labeled orthophosphate, then challenged with secretory stimuli. A postmicrosomal supernatant fraction was prepared from the cells and incubated with unlabeled chromaffin granule membranes in the presence of 5 mM Ca2+. Proteins that bound to the membranes were isolated by centrifugation and examined for 32P content by electrophoresis and autoradiography. Stimulation by carbamylcholine, nicotine, 56 mM K+, or 2 mM Ba2+ led to the incorporation of 32P into a 37-kDa protein that had previously been characterized as a substrate for protein kinase C in vitro (chromobindin 9, or CB9; Summers, T. A., and Creutz, C. E. (1985) J. Biol. Chem. 260, 2437-2443). Incorporation of 32P into this protein was dependent on extracellular Ca2+ and followed a time course that paralleled secretion of catecholamines, returning to base-line levels after 30 min, when secretion terminated. 32P was also incorporated into a 58-kDa protein that may be tyrosine hydroxylase and into an unidentified 28-kDa protein in response to cell stimulation, but neither of these proteins bound to granule membranes in a Ca2+-dependent manner. Treatment of cells with phorbol 12,13-dibutyrate, an activator of protein kinase C, led to 32P incorporation into the 37-kDa protein that was only 30% of the level obtained with nicotinic stimulation, suggesting that additional kinases may be involved in phosphorylating this protein in the stimulated cell.
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PMID:Phosphorylation of a chromaffin granule-binding protein in stimulated chromaffin cells. 370 Apr 8

Incubation of rat liver plasma membrane produced histone phosphorylating activity at 75 mM Mg2+ in the soluble fraction. The release of the kinase activity was inhibited by leupeptin and bovine pancreatic trypsin inhibitor, suggesting the involvement of membrane-bound protease. When partially purified protein kinase C from rat liver cytosol was treated with the trypsin-like protease purified from rat liver plasma membrane, histone phosphorylating kinase which was independent of Ca2+ and phospholipids, produced with a molecular weight of about 5 X 10(4). These results suggest that membrane-bound, trypsin-like protease activates protein kinase C in plasma membrane and the activated kinase is released from the membrane to the soluble fraction.
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PMID:Proteolytic activation of protein kinase C by membrane-bound protease in rat liver plasma membrane. 390 21


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