EC:2.7.11.13 - FACTA Search

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)

Previous studies from our laboratory demonstrated that high-density lipoproteins (subclass 3; HDL3) bind to sites specific for apolipoprotein AI on the human adenocarcinoma cell line A549 and that HDL3 binding promotes a mitogenic effect [Favre, Tazi, Le Gaillard, Bennis, Hachem and Soula (1993) J. Lipid Res. 34, 1093-1106]. In the present study, we have examined the cell proteins that showed modified phosphorylation after binding of HDL3 to specific sites, and the roles of Ca2+ and protein kinase C. Native HDL3 (but not tetranitromethane-modified HDL3) and Ca2+ ionophore A23187 strongly enhanced the phosphorylation of a 20 kDa protein (x 3.6) and, to a lower extent, the phosphorylation of 24 and 28 kDa proteins (x 2.2 and 2.6 respectively). The two effectors were equally able to stimulate cell growth. Down-regulation of protein kinase C by a 24 h incubation of cells with phorbol myristate acetate prevented the effects of HDL3 on the phosphorylation of 24 and 28 kDa proteins. However, the extent of phosphorylation of the 20 kDa protein was not affected. In contrast, activation of protein kinase C by a short incubation with phorbol myristate acetate resulted in inhibition of proliferation and an increase in 24 and 28 kDa (but not 20 kDa) protein phosphorylation. These results suggest that HDL3 putative receptors exert their proliferative effect on A549 cells through activation of a Ca(2+)-dependent protein kinase. This kinase activity is not modulated by phorbol ester and thus may be a calmodulin kinase or an isoenzyme of protein kinase C that is independent of phorbol ester. It allows a subsequent 20 kDa protein to be phosphorylated.
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PMID:Involvement of the Ca(2+)-dependent phosphorylation of a 20 kDa protein in the proliferative effect of high-density lipoproteins (subclass 3) on the adenocarcinoma cell line A549. 773 97

HASPP28 (heat- and acid-stable phosphoprotein of 28 kDa) has been purified to near homogeneity from the acid-stable protein fraction of rat brain extract. Based on the N-terminal 40 amino acid sequence, a pair of highly degenerate primers was used to generate a 107-bp probe from rat brain RNA by RT-PCR. From the rat brain lambda gt11 library, this probe identified two positive clones that together provided a cDNA of 837 bp with an open reading frame of 546 bp. This cDNA was extended by 3'RACE to 1.2 kb that included a polyadenylation signal and a poly(A) tail. The 180-amino-acid sequence derived from the open reading frame, which did not correspond to any known protein, was predicted to have phosphorylation sites for protein kinase C, casein kinase II (CKII), and protein kinase A. Indeed, both the purified rat brain HASPP28 and the recombinant HASPP28 (rHASPP28) can be phosphorylated by these kinases. Northern blot analysis indicated that HASPP28 was present in all rat tissues tested, including those from the brain, lung, spleen, kidney, liver, heart, and muscle, in decreasing order of abundance. Phosphopeptide analysis of rHASPP28 phosphorylated in vitro by various kinases showed different tryptic patterns on two-dimensional mapping and isoelectric focusing gels. From [32P]PO4-labeled N1E115 neuroblastoma cells, HASPP28 can be immunoprecipitated with a polyclonal antiserum raised against rHASPP28. The immunoprecipitated protein showed a phosphopeptide pattern similar to that of rHASPP28 phosphorylated by CK II in vitro. Furthermore, the immunoprecipitates from cells treated with phorbol 12-myristate 13-acetate or 8-bromo-cAMP did not show any increased phosphorylation over those of untreated ones, and the phosphopeptide patterns of the immunoprecipitates again were similar to that of CK II phosphorylated protein. These results suggest that HASPP28 is a novel phosphoprotein that can be phosphorylated by several kinases in vitro. In intact cells, CK II seems to be solely responsible for the phosphorylation of HASPP28.
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PMID:Molecular cloning and characterization of a novel casein kinase II substrate, HASPP28, from rat brain. 861 83

Angiotensin II (AII) was found to upregulate tissue inhibitor of metalloproteineses-1 (TIMP-1) gene expression in rat heart endothelial cells in a dose and time-dependent manner. The maximal stimulation of TIMP-1 mRNA was achieved by 2 h after the addition of AII. This effect was blocked by losartan, an AT1 receptor antagonist and by calphostin C, a protein kinase C inhibitor. Addition of cycloheximide superinduced and actinomycin D abolished the induction. These results suggest that AII stimulates TIMP-1 production by a protein kinase C dependent pathway which is dependent upon de novo RNA synthesis. Immunoprecipitation experiment showed an enhanced band of 28 kDa from the conditioned medium of AII-treated cultures. Immunoblot analysis revealed that TIMP-1 was detectable in the conditioned medium 4 h after AII stimulation. Since endothelial cells line the blood vessels and sense the rise in AII associated with hypertension, the TIMP-1 released by these cells may provide an initial trigger leading to cardiac fibrosis in angiotensin-renin dependent hypertension.
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PMID:Angiotensin II induces TIMP-1 production in rat heart endothelial cells. 866 44

The major substrate of protein kinase C(PKC) in platelets is the 40 kDa protein, pleckstrin. Addition of the homobifunctional reagent, bis(sulphosuccinimidyl)suberate (BS3), to platelet lysate, cytosol fraction or to electropermeabilized platelets resulted in cross-linking of pleckstrin to give higher-molecular-mass complexes of 68 kDa, 90 kDa and 100-120 kDa respectively, which were visualized by immunoblotting with an anti-pleckstrin antibody. Higher levels of cross-linking were observed in permeabilized platelets than in platelet lysates. The yields of the cross-linked complexes were much reduced after dilution of platelet lysate or lysis of electropermeabilized platelets and, in the case of the 90 kDa and 100-120 kDa species, after activation of PKC by phorbol 12-myristate 13-acetate. Similar experiments with purified pleckstrin indicated that the 90 kDa and 100-120 kDa species consist, at least in part, of pleckstrin dimers and higher oligomers. After incubation of purified pleckstrin (0.45 mg/ml) for 1 h with 2 mM BS3, about 25% of the protein was present in cross-linked species. The results indicate that pleckstrin undergoes a reversible self-association that can be prevented by phosphorylation of the protein, and also interacts with an unidentified platelet protein of about 28 kDa.
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PMID:Chemical cross-linking of pleckstrin in human platelets: evidence for oligomerization of the protein and its dissociation by protein kinase C. 869 52

Calbindin-D28K is a vitamin D3 dependent calcium-binding protein expressed in renal distal tubules. We previously reported that 24 h treatment with 1 alpha, 25-dihydroxyvitamin D3 (1,25-D3), the active form of vitamin D3, induces calbindin-D28K and activates protein kinase C (PKC) in MDBK (Madin-Darby bovine kidney) cells. In contrast, 24 h treatment with the phorbol ester 12-O-tetradecanoylphorbol-3-acetate (TPA) downregulates calbindin-D28K and PKC activity. In the present studies, we demonstrate that TPA rapidly enhances calbindin-D28K expression in MDBK cells in the absence of 1,25-D3. The enhancement of calbindin-D28K expression is preceded by activation and translocation of PKC alpha. Further, we show that PKC directly phosphorylates calbindin-D28K in a calcium- and phospholipid-dependent manner in vitro. In MDBK cells, the calbindin-D28K antibody immunoprecipitates a 28 kDa protein for which phosphorylation is enhanced after treatment for 1 h with TPA or 24 h with 1,25-D3. Consistent with amino acid sequence analysis of calbindin-D28K indicating two threonine residues that fit the consensus for PKC phosphorylation, TPA-treated MDBK cells exhibit enhanced expression of a phosphothreonine-containing protein that co-migrates with calbindin-D28K. These studies offer the first report that calbindin-D28K is a phosphoprotein and implicate the PKC signal transduction pathway in its regulation.
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PMID:Modulation and phosphorylation of calbindin-D28K correlates with protein kinase C activation1. 919 71

Lipid-soluble psychotropics are often used to treat skin diseases with psychosomatic indications. Although these drugs are known to exert their effects through the central nervous system, relatively little is known about their mechanism of action in skin. In this communication, several lipid-soluble psychotropic drugs have been examined for their ability to inhibit protein kinase C (PKC)-catalyzed phosphorylation of exogenous substrates and endogenous skin proteins. Phosphorylation of three discrete skin protein substrates at 64, 42 and 28 kDa and a group crowded together at 15-18 kDa was prevented by the antidepressants/antipsychotics. Inhibition was more pronounced in a phospholipid (PL) dependent system, but both drug-PL and drug-PKC interactions seem to be important in the mechanism of action of these drugs. In addition to the tricyclic nucleus, the propanamine side chain or its N-methyl form may influence the interaction of these drugs with PKC and its substrate(s). Chlorpromazine, imipramine, fluoxetine, doxepin, amitriptyline and hydroxyzine used in the practice of dermatology may exert their therapeutic effects by modulating skin PKC activity.
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PMID:Inhibition of skin protein kinase C by psychotropic drugs. 941 93

Small heat-shock proteins (sHSPs) are widely expressed 25-28 kDa proteins whose functions are dynamically regulated by phosphorylation. While recent efforts have clearly delineated a stress-responsive p38 mitogen-activated protein-kinase (MAPK)-dependent kinase pathway culminating in activation of the heat-shock (HSP)-kinases, mitogen-activated protein-kinase-activated protein kinase-2 and -3, not all sHSP phosphorylation events can be explained by the p38 MAPK-dependent pathway. The contribution of protein kinase C (PKC) to sHSP phosphorylation was suggested by early studies but later questioned on the basis of the reported poor ability of purified PKC to phosphorylate sHSP in vitro. The current study re-evaluates the role of PKC in sHSP phosphorylation in the light of the isoform complexity of the PKC family. We evaluated the sHSP phosphorylation status in rat corpora lutea obtained from two stages of pregnancy, mid-pregnancy and late-pregnancy, which express different levels of the novel PKC isoform, PKC-delta. Two-dimensional Western blot analysis showed that HSP-27 was more highly phosphorylated in vivo in corpora lutea of late pregnancy, corresponding to the developmental stage in which PKC-delta is abundant and active. Late-pregnant luteal extracts contained a lipid-sensitive HSP-kinase activity which exactly co-purified with PKC-delta using hydroxyapatite and S-Sepharose column chromatography. To determine whether there might be preferential phosphorylation of sHSP by a particular PKC isoform, purified recombinant PKC isoforms corresponding to those PKC isoforms detected in rat corpora lutea were evaluated for HSP-kinase activity in vitro. Recombinant PKC-delta effectively catalysed the phosphorylation of sHSP in vitro, and PKC-alpha was 30-50% as effective as an HSP-kinase; other PKCs tested (beta1, beta2, epsilon and zeta) were poor HSP-kinases. These results show that select PKC family members can function as direct HSP-kinases in vitro. Moreover, the observation of enhanced luteal HSP-27 phosphorylation in vivo, in late pregnancy, when PKC-delta is abundant and active, suggests that select PKC family members contribute to sHSP phosphorylation events in vivo.
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PMID:Heat-shock protein-25/27 phosphorylation by the delta isoform of protein kinase C. 962 Aug 73

Betacellulin belongs to the family of epidermal growth factor-like growth factors that are expressed as transmembrane precursors and undergo proteolytic ectodomain shedding to release a soluble mature growth factor. In this study, we investigated the ectodomain shedding of the betacellulin precursor (pro-BTC) in conditionally immortalized wild-type (WT) and ADAM-deficient cell lines. Sequential ectodomain cleavage of the predominant cell-surface 40-kDa form of pro-BTC generated a major (26-28 kDa) and two minor (20 and 15 kDa) soluble forms and a cellular remnant lacking the ectodomain (12 kDa). Pro-BTC shedding was activated by calcium ionophore (A23187) and by the metalloprotease activator p-aminophenylmercuric acetate (APMA), but not by phorbol esters. Culturing cells in calcium-free medium or with the protein kinase Cdelta inhibitor rottlerin, but not with broad-based protein kinase C inhibitors, blocked A23187-activated pro-BTC shedding. These same treatments were without effect for constitutive and APMA-induced cleavage events. All pro-BTC shedding was blocked by treatment with a broad-spectrum metalloprotease inhibitor (GM6001). In addition, constitutive and activated pro-BTC shedding was differentially blocked by TIMP-1 or TIMP-3, but was insensitive to treatment with TIMP-2. Pro-BTC shedding was functional in cells from ADAM17- and ADAM9-deficient mice and in cells overexpressing WT or catalytically inactive ADAM17. In contrast, overexpression of WT ADAM10 enhanced constitutive and activated shedding of pro-BTC, whereas overexpression of catalytically inactive ADAM10 reduced shedding. These results demonstrate, for the first time, activated pro-BTC shedding in response to extracellular calcium influx and APMA and provide evidence that ADAM10 mediates constitutive and activated pro-BTC shedding.
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PMID:ADAM10 mediates ectodomain shedding of the betacellulin precursor activated by p-aminophenylmercuric acetate and extracellular calcium influx. 1550 48

Calpains are a family of calcium-dependent cysteine-proteases involved in cytoskeleton remodelling and muscle differentiation. In a recent study, we observed the presence of calpain 1 in the muscle contractile apparatus and specifically in the N1- and N2-lines. This calpain isoform was found to be involved in the degradation of muscle fibres via proteolysis of key proteins in Z-disk and costameric junctions. The goal of this study was to determine whether gamma-filamin--a specific muscle isoform of the filamin family--is a calpain 1 substrate and to characterise this interaction. Gamma-filamin is a major muscle architectural protein located in the Z-line and under the sarcolemmal membrane. This protein is a component of the chain binding the sarcolemma to the sarcomeric structure. In this study, we found that gamma-filamin formed a stable complex in vitro and in cells with calpain 1 in the absence of calcium stimulation. We also located the binding domains in the C-terminus of gamma-filamin with a cleavage site between serine 2626 and serine 2627 in the hinge 2 region. The catalytic (80 kDa) and regulatory (28 kDa) subunits of calpain 1 are both involved in high affinity binding at gamma-filamin. Moreover, we showed that phosphorylation of the filamin C-terminus domain by PKC alpha protected gamma-filamin against proteolysis by calpain 1 in COS cells. Stimulation of PKC activity in myotubes, prevented gamma-filamin proteolysis by calpain and resulted in an increase in myotube adhesion.
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PMID:Calpain 1-gamma filamin interaction in muscle cells: a possible in situ regulation by PKC-alpha. 1629 52

The neuron-specific phosphoprotein B-50 (= GAP-43/F1/pp46/P57) is an endogenous substrate of protein kinase C (PKC) in rat brain. To examine the location of the PKC phosphosites, phosphorylated B-50 was digested by Staphylococcus aureus V8 protease (SAP). The products migrated in SDS-polyacrylamide gel electrophoresis as two phosphoprotein bands of apparent molecular weight of 15 and 28 kDa (indicated as 15 and 28 K). This study reports further characterization of the 15 and 28 K phosphobands. ACTH(1-24), a characteristic inhibitor, inhibited equally effective the [(32)P]phosphate-incorporation into the 15 and 28 K phosphobands formed by SAP from B-50 endogenously phosphorylated in synaptosomal plasma membrane (SPM). Tests using immunoprecipitation or immunoblotting showed that all polyclonal rabbit B-50 antisera recognized the 28 K phosphoband, but only a minor population B-50 antibodies of a recently developed antiserum 8613 reacted with the 15 K phosphoband. The time course of the SAP digestion indicated that B-50 is degraded first to the 28 K band and then to the 15 K band. [(32)P]phosphate incorporated in B-50 was totally recovered in these phosphobands. Isoelectric focusing resolved the SAP products into one 28 K phosphopeptide of isoelectric point (IEP) 4.8 and the 15 K phosphofragment in at least 4 phosphopeptides, with IEP of 6.1, 6.6, 6.9 and 7.0, respectively. SAP digests of extensively phosphorylated B-50 analysed by isoelectric focusing in narrow pH gradients, showed microheterogeneity in the undigested B-50, the 28 and 15 K phosphofragments. The time course of SAP digestion of B-50 in endogenously phosphorylated SPM and in phosphorylated nerve growth cone membranes, demonstrated that in both types of membranes, 28 and 15 K phosphofragments are consecutively formed, with IEP identical to the phosphofragments derived from isolated B-50. Our findings suggest that the PKC phosphosite(s) in the B-50 protein are restricted to neutral 15 K peptides of the B-50 molecule.
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PMID:The protein kinase C phosphosite(s) in B-50 (GAP-43) are confined to 15K phosphofragments produced by Staphylococcus aureus V8 protease. 2050 38

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