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)

Protein kinase C(PKC) activity in macrophages and polymorphonuclear leukocytes was assayed in beige mouse, the model of Chediak-Higashi syndrome, control C57BL/6 and the heterozygous (+/bg) mice. Regarding enzyme activity in the cytosolic and membrane fractions of these cells, there was no difference between beige mouse and the control. After short-term activation by TPA, the translocated membrane-bound PKC activity in beige mouse decreased rapidly compared with that in control mouse. However, the cytosolic PKC activity decreased at just the same pace as the control. The change in [3H] PDBu binding paralleled the changes in PKC activity. An increase in Ca2+/phospholipid-independent protein kinase by TPA was notable in the membrane fraction of beige mouse. The increase in the kinase activity was abolished and the PKC activity recovered to normal level by the addition of calpain inhibitor, leupeptin, to the incubation of cells along with TPA. Therefore, these findings suggest that a rapid decrease in membrane-bound PKC activity in beige mouse by TPA stimulation is associated with calpain.
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PMID:Rapid down-regulation of protein kinase C in (Chediak-Higashi syndrome) beige mouse by phorbol ester. 338 95

We examined the interdependence of calpain and protein kinase C (PKC) activities on neurite outgrowth in SH-SY-5Y human neuroblastoma cells. SH-SY-5Y cells elaborated neurites when deprived of serum or after a specific thrombin inhibitor, hirudin, was added to serum-containing medium. The extent of neurite outgrowth under these conditions was enhanced by treatment of cells with the cell-permeant cysteine protease inhibitors N-acetyl-leucyl-leucyl-norleucinal ("C1") and calpeptin or by the phospholipid-mediated intracellular delivery of either a recombinant peptide corresponding to a conserved inhibitory sequence of human calpastatin or a neutralizing anti-calpain antisera. Calpain inhibition in intact cells was confirmed by immunoblot analysis showing inhibition of calpain autolysis and reduced proteolysis of the known calpain substrates fodrin and microtubule-associated protein 1. The above inhibitory peptides and antiserum did not induce neurites in medium containing serum but lacking hirudin, suggesting that increased surface protein adhesiveness is a prerequisite for enhancement of neurite outgrowth by calpain inhibition. Treatment of cells with the PKC inhibitor H7, staurosporine, or sphingosine induced neurite outgrowth independently of serum concentration. Because calpain is thought to regulate PKC activity, we examined this potential interrelationship during neurite outgrowth. Simultaneous treatment with calpain and PKC inhibitors did not produce additive or synergistic effects on neurite outgrowth. PKC activation by 2-O-tetradecanoylphorbol 13-acetate (TPA) prevented and reversed both neurite initiation by serum deprivation and its enhancement by calpain inhibitors. Treatment of cells with the calpain inhibitor C1 retarded PKC down-regulation following TPA treatment. Cell-free analyses demonstrated the relative specificity of various protease and kinase inhibitors for calpain and PKC and confirmed the ability of millimolar calcium-requiring calpain to cleave the SH-SY-5Y PKC regulatory subunit from the catalytic subunit, yielding a free catalytic subunit (protein kinase M). These findings suggest that the influence of PKC on neurite outgrowth is downstream from that of surface adhesiveness and calpain activity.
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PMID:Enhancement of neurite outgrowth following calpain inhibition is mediated by protein kinase C. 761 5

Endogenous calcium-activated proteases, the calpains, are thought to play a role in the regulation of postsynaptic function. Here we characterize some biochemical and morphological effects of calpain on isolated postsynaptic densities (PSDs). When a PSD preparation from rat forebrain was treated with exogenous calpain, many proteins, including spectrin, tubulin and the alpha-subunit of calcium calmodulin-dependent protein kinase (alpha-CaM kinase), were proteolyzed at varying rates, while another major protein, actin, remained intact. The selectivity of calpain action became more apparent in experiments designed to achieve limited proteolysis by using a lower calpain-to-protein ratio; it was possible to obtain extensive breakdown of spectrin with no decrease in the levels of either tubulin, alpha-CaM kinase, or actin. Electron microscopy of freeze-substituted preparations showed that limited calpain action caused a partial unraveling of the PSD, in which the characteristic central dense lamina became wider and less dense. We interpret these changes as due to calpain-mediated breakdown of cross-bridging elements, leading to a partial unraveling of the central PSD lamina. Opening up of the PSD structure following limited calpain action could facilitate exposure of previously occluded functional sites within the PSD and contribute to the modification of the synaptic function.
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PMID:Effect of calpain on the composition and structure of postsynaptic densities. 762 34

The degradation of troponin (Tn) subunits by calpain was studied by incubating either isolated cardiac Tns or myocardial cryosections with two different calpain isoenzymes isolated from rat skeletal muscle. Western-blot analysis with monoclonal antibodies against TnI and TnT showed that mu-calpain was at least ten times more active than m-calpain in degrading TnI and TnT both in vitro and in situ. TnC was completely resistant to both proteinase forms. Phosphorylation by cyclic AMP-dependent protein kinase (PKA) isolated from rat skeletal muscle reduced the sensitivity of TnI to degradation. This effect in combination with an increased efficiency of the endogenous inhibitor [Salamino, De Tullio, Michetti, Mengotti, Melloni and Pontremoli (1994) Biochem. Biophys. Res. Commun. 199, 1326-1332] probably reduces the proteolytic activity of calpain in cells on PKA stimulation. Conversely, phosphorylation by protein kinase C (PKC) resulted in a twofold increase in the degradation of TnI. Degradation by m-calpain was not modified by Tn phosphorylation. The different sensitivity to mu-calpain might be related to changes in TnI oligomeric structure. Indeed, on PKC phosphorylation, the apparent molecular mass of TnI calculated from the distribution coefficient of Tn complex in Sephadex G-100 matrix was reduced from 90 to 30 kDa suggesting dissociation of the Tn complex.
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PMID:Specific degradation of troponin T and I by mu-calpain and its modulation by substrate phosphorylation. 775 88

Phosphorylation of calpain II (or its inhibitor) by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK), cyclic GMP-dependent protein kinase (G-PK), and protein kinase C (PK-C) was analyzed by SDS-polyacrylamide gel electrophoresis and autoradiography. Among these protein kinases, the catalytic subunit of A-PK exhibited the strongest phosphorylations of both calpain II and its inhibitor. Arachidonic acid and staurosporine effectively inhibited phosphorylation regardless the type of kinase tested. Despite its lack of effect on the phosphorylation of calpain II by the catalytic subunit of A-PK, sphingosine moderately enhanced the phosphorylation of calpain II by G-PK. Other agents, including phosphatidylethanolamine, phosphatidylinositol and 1, 2-dioleoyl-sn-glycerol, had no significant effect.
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PMID:Regulation of the phosphorylation of calpain II and its inhibitor. 784 69

Three enzymes relevant to signal transduction were compared in replicating, quiescent and senescent human diploid fibroblasts (HDF). These were Ca(2+)-dependent thiol protease (calpain), cAMP-dependent protein kinase (Pk-A), and calcium/phospholipid-dependent protein kinase C (Pk-C). The amounts of these enzymes in quiescent HDF were slightly greater or the same as in replicating HDF. In contrast, senescent HDF exhibited higher Pk-C, Pk-A and proteolytic activities than did either replicating or quiescent cells. While the elevated protein kinase activities could be accounted for by the larger size of senescent cells relative to younger cells, the increased calpain activity exceeded this size differential. Immunoblotting studies with antisera to both Pk-C and calpain demonstrated increased enzyme concentrations in parallel with the increased activities. Photolabeling cell extracts with an analog of cAMP, 8-N3-[32P]cAMP, provides an estimate of Pk-A concentration. By this criterion, senescent HDF have more Pk-A molecules than do young cells that are either replicating or quiescent. Only the type I isozyme of Pk-A (Pk-A-I) was observed in any of these cells. Photolabeling with 8-N3-[32P]cAMP demonstrated more degradative fragments of the Pk-A regulatory subunit (RI) in senescent cells also. This is a logical consequence of the increased calpain activity in senescent cells, since RI is a substrate for calpain. These results imply that senescent cells do not fail to enter S phase owing to inadequate concentrations of Pk-A or Pk-C. Rather, the increased quantities of these enzymes in senescent cells may reflect aberrations elsewhere along signal transduction pathways that coordinate cell size with cell proliferation.
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PMID:Serine/threonine protein kinases and calcium-dependent protease in senescent IMR-90 fibroblasts. 811 16

Two calpastatins, with Mr 110 KD and named calpastatin I and II, have been isolated from rat heart and kidney and displayed distinct inhibitory efficiency with mu- and m-calpain, respectively, as those isolated from rat skeletal muscle. Whereas the level of calpastatin I always exceeds that of mu-calpain, the level of calpastatin II appears to be more closely correlated to the level of m-calpain. As previously shown for skeletal muscle, the two inhibitor proteins can be interconverted by a phosphorylation-dephosphorylation reaction; the enzyme responsible for phosphate incorporation in calpastatin I is now identified in c-AMP dependent protein kinase A. In rat erythrocytes, containing a single calpain form, the single low Mr calpastatin form does not undergo reversible phosphorylation and is equally efficient in respect to typical mu- and m-calpain. The presence of two interconvertible calpastatin forms provides the cells with a highly sensitive mechanism of regulation of the Ca(2+)-dependent proteolytic system.
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PMID:Modulation of calpastatin specificity in rat tissues by reversible phosphorylation and dephosphorylation. 814 76

The proteolysis of the 32P-labeled holoenzyme of cyclic AMP-dependent protein kinase (A-PKII:DEAE, peak II fraction) was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The contaminants of the A-PKII and calpain II apparently did not interfere with the accuracy of this highly sensitive analysis. Phosphorylation of calpain II by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) greatly enhanced the proteolysis of A-PKII, whereas phosphorylation by protein kinase C (PK-C) or cyclic GMP-dependent protein kinase (G-PK) slightly altered the proteolysis.
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PMID:Modulation of the activity of calpain II by phosphorylation--changes in the proteolysis of cyclic AMP-dependent protein kinase (peak II, DEAE). 819 24

This laboratory has been characterizing protein serine/threonine kinase reactions of hematopoietic tissues, whose most distinguishing characteristics in vitro are stimulation with vesicular phosphatidyl glycerol, and the ability to function using Mn2+ as the sole divalent cation. The major protein substrates are a 73-kD protein and a protein migrating near ovalbumin on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The 47-kD protein was partially purified from cells harvested by leukapheresis from a patient with acute myelogenous leukemia, using ammonium sulfate precipitation and ion exchange chromatography. This partially purified ion-exchange fraction contained an endogenous kinase activity with characteristics similar to those we previously described of protein kinase P (protein kinase, phospholipid-stimulable: PK-P), but not typical of any form of protein kinase C (PK-C). With longer phosphorylation, the 47-kD band showed increasingly lower mobility demonstrable both by Coomassie blue staining and autoradiography, suggesting both that it was multiply phosphorylated, and that the excisable band was pure. The protein was thus eluted from preparative gel slices and digested with endoproteinase lys C. Sequence data from the fragments identified the protein as the 47-kD calpain fragment of talin, a protein found in focal adhesion plaques and some cell-cell contacts. PK-C phosphorylated the 47-kD protein, as has been reported previously, and phosphopeptide mapping disclosed a similar pattern of phosphorylation using either PK-C or the endogenous activity. The 47-kD protein labeled with the endogenous kinase contained predominantly phosphoserine, with some phosphothreonine and a trace of phosphotyrosine. Intact, purified talin was also phosphorylated by PK-P in a phospholipid-stimulable manner, but at 1/20 the rate of the 47-kD fragment.
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PMID:The 47-kD fragment of talin is a substrate for protein kinase P. 824 4

The phosphorylation of histones and glycogen synthase by protein kinases was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The phosphorylation of histone III-S by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) or cGMP-dependent protein kinase (G-PK) was inhibited by archidonic acid, sphingosine and staurosporine. Using the catalytic subunit of A-PK, the phosphorylation of histone VIII-S was inhibited by Ca2+, arachidonic acid and staurosporine; the phosphorylation of histone II-S was inhibited by phosphatidyl ethanolamine, phosphatidyl inositol, arachidonic acid and staurosporine; and the phosphorylation of glycogen synthase was inhibited by arachidonic acid and staurosporine. After being phosphorylated by the catalytic subunit of A-PK, calpain II with 4 microM Ca2+ was less effective in degrading histone III-S, which had been prephosphorylated by PK-C.
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PMID:Regulation of the phosphorylation of histones and glycogen synthase. 824 12


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