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)

In this study we describe the activation of a protein kinase which phosphorylates a peptide, T669, comprising amino acids 663-681 of the epidermal growth factor receptor and containing the phosphate acceptor site Pro-Leu-Thr669-Pro. In the human epidermoid carcinoma cell line KB, T669 kinase activity in cytosolic extracts peaked (up to 15-fold compared with basal levels) 15-30 min after addition of interleukin-1 (IL-1) and closely paralleled receptor occupancy with a half-maximally effective concentration of approximately 100 pM IL-1 alpha. IL-1 treatment elevated T669 kinase activity to a variable extent in selected fibroblast lines, the hepatoma cell line HepG2, and the murine thymoma EL4 6.1. An IL-1 receptor-negative EL4 variant and the B cell lines 70Z/3, CB23, and RPMI 1788 did not respond in this way. All of the cell lines except 70Z/3 showed increased levels of T669 kinase when treated with the protein kinase C activator phorbol myristate acetate and/or with epidermal growth factor. This finding is in agreement with a previous study (Countaway, J. L., Northwood, I. C., and Davis, R. J. (1989) J. Biol. Chem. 264, 10828-10835). Activators of protein kinase A did not mimic the ability of IL-1 to stimulate T669 kinase activity, nor did the protein kinase C inhibitor staurosporine abrogate the effect of IL-1. T669 kinase activity from IL-1-stimulated KB cells was partially purified by ion exchange, hydrophobic interaction, and size exclusion chromatography. The partially purified enzyme phosphorylated myelin basic protein, a characteristic substrate of microtubule-associated protein-2 kinase (MAP-2 kinase) and the peptide Arg-Arg-Arg-(Tyr-Ser-Pro-Thr-Ser-Pro-Ser)4 from RNA polymerase II. Western blotting of chromatographic fractions revealed that T669 kinase activity corresponded with two proteins of 43 and 45 kilodaltons which cross-reacted with antibodies raised against peptide sequences of rat extracellular signal-regulated kinase-1/microtubule-associated protein-2 kinase. T669 kinase activity was critically dependent on the presence of phosphatase inhibitors. Since both the 43- and 45-kDa proteins, immunoprecipitated from [32P]phosphate-labeled cells, demonstrated a dramatic increase in their levels of serine, threonine, and tyrosine phosphorylation after brief treatment with IL-1, we conclude that IL-1 modulates the activity of these extracellular signal-regulated kinase/microtubule-associated protein-2 kinases by altering the level of their phosphorylation.
 ...
PMID:Interleukin-1 represents a new modality for the activation of extracellular signal-regulated kinases/microtubule-associated protein-2 kinases. 165 5

Voltage-gated sodium channels are responsible for generation of action potentials in excitable cells. Activation of protein kinase C slows inactivation of sodium channels and reduces peak sodium currents. Phosphorylation of a single residue, serine 1506, that is located in the conserved intracellular loop between domains III and IV and is involved in inactivation of the sodium channel, is required for both modulatory effects. Mutant sodium channels lacking this phosphorylation site have normal functional properties in unstimulated cells but do not respond to activation of protein kinase C. Phosphorylation of this conserved site in sodium channel alpha subunits may regulate electrical activity in a wide range of excitable cells.
 ...
PMID:A phosphorylation site in the Na+ channel required for modulation by protein kinase C. 165 37

The human recombinant CRE-BP1 was phosphorylated by cAMP-dependent protein kinase and protein kinase C, in vitro. These two protein kinases modified distinct serine residues of CRE-BP1. Ser-62 downstream of a putative metal finger structure of CRE-BP1 was the phosphorylation site by cAMP-dependent protein kinase, whereas two serine residues, Ser-340 and Ser-367, located in the basic region of this protein were the major protein kinase C phosphorylation sites. It seems possible that transcriptional and DNA-binding activities of CRE-BP1 are regulated by phosphorylation with these protein kinases.
 ...
PMID:Phosphorylation of cAMP response element-binding protein, CRE-BP1, by cAMP-dependent protein kinase and protein kinase C. 166 85

The pathways depicted in Figure 1 summarize the data discussed in this article. In neurons, the binding of insulin and IGF-I to their respective receptors triggers autophosphorylation of the receptor beta-subunits. IGF-II binds to both neuronal insulin and IGF-I receptors and can stimulate autophosphorylation of either receptor type. In addition to enhancing insulin and IGF-I receptor autophosphorylation, all 3 peptides stimulate the tyrosine phosphorylation of a 70 kDa protein with a similar time course and dose response to receptor phosphorylation. The identity of pp70 is unknown, although the close temporal relationship between pp70 phosphorylation and neurite outgrowth suggests a potential role for this protein. Subsequent to these very early events, two neuronal serine kinases are activated by insulin. One has S6 kinase activity and may represent either the pp90rsk or pp70 class of S6 kinases. Since S6 kinases are activated by direct phosphorylation rather than by second messengers, it is likely that a neuronal S6 kinase kinase exists. The activation of S6 kinase is likely to mediate insulin's effects on neuronal protein synthesis or other growth-related processes. The second serine kinase that is activated by insulin is PKC epsilon. This enzyme is largely restricted to the nervous system, so this signalling pathway may be neuronal-specific. The mechanism of activation of PKC epsilon is unknown, although preliminary data suggests that enhanced phosphorylation of the enzyme is involved. Studies are currently underway to investigate the potential role of diacylglycerol, a potential second messenger generated from either phosphotidylinositol or phosphotidylcholine hydrolysis, in the activation of PKC epsilon by insulin.
 ...
PMID:Regulation of protein phosphorylation by insulin and insulin-like growth factors in cultured fetal neurons. 166 64

Endogenous phosphorylation of the crude membrane fraction of cultured 3Y1 fibroblast cells was enhanced by the addition of Ca2+/calmodulin. Both Ca2+/calmodulin-dependent protein kinase activity and its substrate were present in a cytoskeletal fraction, obtained as a pellet after washing of the membrane fraction with 2 mM EGTA, 0.6 M NaCl, and 1% Triton X-100. The phosphorylatable protein in the Triton X-insoluble fraction was identified by immunoblotting as vimentin. This endogenous phosphorylation induced by calmodulin was inhibited by the addition of KN-62, a specific Ca2+/calmodulin-dependent protein kinase II inhibitor, in a dose-dependent manner. However, phosphorylation of the 59 kDa protein (vimentin) in this fraction was not stimulated by adding both phosphatidyl serine and cAMP, thereby suggesting the absence of protein kinase C or of cAMP-dependent protein kinase in this fraction. The protein kinase associated with the Triton X-insoluble fraction phosphorylated the Ca2+/calmodulin-dependent protein kinase II-specific site of synapsin I from the bovine cortex. Two-dimensional phosphopeptide maps of vimentin indicated that a major phosphopeptide phosphorylated by the endogenous calmodulin-dependent kinase also appears to be the same as a major phosphopeptide phosphorylated by the exogenous Ca2+/calmodulin-dependent protein kinase II. Our results suggest that cytoskeleton-associated Ca2+/calmodulin-dependent protein kinase II regulates dynamic cellular functions through the phosphorylation of cytoskeletal elements in non-neural cells.
 ...
PMID:Ca2+/calmodulin-dependent protein phosphorylation associated with the cytoskeleton of quiescent rat fibroblast (3Y1) cells. 166 12

The alpha subunit of eukaryotic protein synthesis initiation factor (eIF-2 alpha) is phosphorylated at a single serine residue (Ser51) by two distinct and well-characterized protein kinase, the haem-controlled repressor (HCR) and the double-stranded RNA-activated inhibitor (dsI). The sequence adjacent to Ser51 is rich in basic residues (Ser51-Arg-Arg-Arg-Ile-Arg) suggesting that they may be important in the substrate specificity of the two kinases, as is the case for several other protein kinases. A number of proteins and synthetic peptides containing clusters of basic residues were tested as substrates for HCR and dsI. Both kinases were able to phosphorylate histones and protamines ar multiple sites as judged by two-dimensional mapping of the tryptic phosphopeptides. These data also showed that the specificities of the two kinases were different from one another and from the specificities of two other protein kinases which recognise basic residues, cAMP-dependent protein kinase and protein kinase C. In histones, HCR phosphorylated only serine residues while dsI phosphorylated serine and threonine. Based on phosphoamino acid analyses and gel filtration of tryptic fragments, dsI was capable of phosphorylating both 'sites' in clupeine Y1 and salmine A1, whereas HCR acted only on the N-terminal cluster of serines in these protamines. The specificities of HCR and dsI were further studied using synthetic peptides with differing configurations of basic residues. Both kinases phosphorylated peptides containing C-terminal clusters of arginines on the 'target' serine residue, provided that they were present at positions +3 and/or +4 relative to Ser51. However, peptides containing only N-terminal basic residues were poor and very poor substrates for dsI and HCR, respectively. These findings are consistent with the disposition of basic residues near the phosphorylation site in eIF-2 alpha and show that the specificities of HCR and dsI differ from other protein kinases whose specificities have been studied.
 ...
PMID:The substrate specificity of protein kinases which phosphorylate the alpha subunit of eukaryotic initiation factor 2. 167 34

P185 is a receptor-like protein encoded by the neu/erbB-2 proto-oncogene. A point mutation in the transmembrane domain renders this protein oncogenic. We report here that incubation of cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulates the phosphorylation of the normal neu protein (p185) and the oncogenic neu protein (p185*). The increased phosphorylation occurs mainly on serine and threonine residues. Phosphate labeling experiments showed that TPA causes a reduction of basal phosphotyrosine in p185 but not p185*. Immunoblotting with antiphosphotyrosine antibody yielded similar results. TPA also inhibited tyrosine phosphorylation of p185* in an in vitro immune complex kinase assay. These data suggest that protein kinase C, the receptor for TPA, regulates p185 function through serine or threonine phosphorylation.
 ...
PMID:TPA inhibits the tyrosine kinase activity of the neu protein in vivo and in vitro. 167 82

A peptide P(45-56) corresponding to residues 45-56 (sequence: ILLSELSRRRIR) of eIF-2 alpha was synthesised. It was phosphorylated by both of the well characterised eIF-2 alpha kinases viz.; the heme-controlled repressor (HCR) and the double stranded RNA-dependent inhibitor (dsI). Of four other protein kinases tested only protein kinase C (PKC) phosphorylated P(45-56), with complete dependence on phosphatidylserine. Only the residue corresponding to serine-51 in eIF-2 alpha was phosphorylated by HCR, dsI or PKC. The phosphorylation of the peptide by dsI and the phosphorylation of eIF-2 alpha by dsI or HCR showed sigmoidal kinetics with respect to substrate concentration.
 ...
PMID:A synthetic peptide substrate for initiation factor-2 kinases. 167 63

Adhesion of activated leukocytes to cells is of critical functional importance. The adhesion is known to be mediated mainly by the CD11/CD18 integrins, also known as leukocytic cell adhesion molecules, or Leu-CAM. We have now studied the phosphorylation of Leu-CAM by protein kinase C and the correlation of phosphorylation with the generation of the adhesive phenotype among human peripheral blood mononuclear leukocytes during cell activation. We here show that a good correlation exists between the phosphorylation of the beta subunit of Leu-CAM (CD18), and the extent of cell-to-cell adhesion. The phosphorylated CD18 subunit was associated with both CD11a and CD11b. Purified protein kinase C was able to phosphorylate the beta subunit of isolated Leu-CAM in vitro. The phosphorylation occurred mainly on serine residues.
 ...
PMID:Phosphorylation of the beta-subunit of CD11/CD18 integrins by protein kinase C correlates with leukocyte adhesion. 168 56

Interleukin 1 or tumor necrosis factor alpha can cause a transient down-modulation of epidermal growth factor (EGF) binding to quiescent fibroblast monolayers; the effect results from a reduction in EGF receptor (EGF-R) affinity and appears to be mediated by a protein kinase C (PKC)-independent mechanism. Here we show transient increases in EGF-R serine/threonine phosphorylation which are temporally coordinated with the effects on EGF binding; we also demonstrate that the cytokine-mediated phosphorylations, unlike those caused by PKC activators, have little discernible effect upon intrinsic EGF-R-associated tyrosine kinase activity. Cytokine-mediated EGF-R phosphorylation is resistant to staurosporine, an extremely potent inhibitor of PKC. Analysis of tryptic 32P-phosphopeptides reveals that Thr654, the unique site of PKC-mediated phosphorylation, is not phosphorylated in cytokine-treated cells, but a different, relatively acidic, peptide containing phosphoserine can be detected instead.
 ...
PMID:Down-modulation of epidermal growth factor receptor affinity in fibroblasts treated with interleukin 1 or tumor necrosis factor is associated with phosphorylation at a site other than threonine 654. 168 28


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