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)

The sheets serve as an maternal supply of assembled, cytokeratin, intermediate filaments. They are remodeled at each major developmental transition in mammalian early development, that is fertilization, embryonic compaction, blastocyst formation, and formation of the primitive ectoderm and primitive endoderm during implantation into the uterine wall. Our results indicate that the sheets exist as specialization for placental development as they have a major role in the maintenance of epithelial integrity at the time the embryo is implanting into the uterine wall. They also contribute intermediate filaments to the junctional complexes required for embryonic compaction. Our analyses demonstrate the they are regulated at the time of fertilization by the action of PKC/PKM, a kinase that acts as a cellular chronometer with both temporal and spatial precision that remodels the egg into the zygote.
 ...
PMID:Remodeling of the specialized intermediate filament network in mammalian eggs and embryos during development: regulation by protein kinase C and protein kinase M. 874 68

To determine if activation of protein kinase C (PKC) participates in the molecular mechanism for agonist induced force enhancement, force was measured in single beta-escin skinned smooth muscle cells stimulated to contract with Ca2+, myosin light chain (MLC) kinase, PKC and microcystin-LR. The constituently active fragment of protein kinase C (PKM) increased both force and MLC phosphorylation in cells previously stimulated to contract at submaximal Ca2+. For cells contracted with saturating Ca2+, PKM stimulation did not increase either force or MLC phosphorylation. For contractions stimulated with both PKM and microcystin-LR, force rose significantly slower than contractions produced by Ca2+ or MLC kinase, suggesting that PKM increases force by a decrease in the rate of myosin dephosphorylation. Consistent with this hypothesis is the finding that the rate of force relaxation was slowed by PKM. This is the first direct demonstration that activation of PKC increases force in smooth muscle, and these results suggest that in smooth muscle, agonist induced activation of PKC plays a role in force regulation via an inhibition of myosin light chain phosphatase activity.
 ...
PMID:Protein kinase C increases force and slows relaxation in smooth muscle: evidence for regulation of the myosin light chain phosphatase. 875 71

Long-term potentiation (LTP) and long-term depression (LTD) are persistent modifications of synaptic efficacy that may contribute to information storage in the CA1 region of the hippocampus. Persistently enhanced phosphorylation has been implicated in the maintenance phase of LTP. This hypothesis is supported by our previous observation that protein kinase M zeta (PKM zeta), the constitutively active catalytic fragment of a single protein kinase C isoform (PKC zeta), increases in LTP maintenance. In contrast, dephosphorylation may be important in LTD maintenance, because phosphatase inhibitors reverse established LTD, in addition to blocking its induction. Because phosphorylation is determined by a balance of phosphatases and kinases, both increases in phosphatase activity and decreases in kinase activity could contribute to LTD. We now report that the reduction of protein kinase activity by H7, as well as selective inhibition of PKC by chelerythrine, mimics and occludes the maintenance phase of homosynaptic LTD in rat hippocampal slices. Conversely, saturated LTD occludes the synaptic depression caused by chelerythrine. Biochemical analysis demonstrates a decrease of PKM zeta, as well as PKCs gamma and epsilon, in LTD maintenance and a concomitant loss of constitutive PKC activity. LTD and the downregulation of PKM zeta are prevented by NMDA receptor antagonists and Ca(2+)-dependent protease inhibitors. Both LTD and the downregulation of PKM zeta are reversible by high-frequency afferent stimulation. Our findings indicate that the molecular mechanisms of LTP and LTD maintenance are inversely related through the bidirectional regulation of PKC.
 ...
PMID:Bidirectional regulation of protein kinase M zeta in the maintenance of long-term potentiation and long-term depression. 875 45

A 3D model of the catalytic domain of PKC was built based on the X-ray structure of the homologous PKA enzyme. The two enzymes were found to have similar general architecture although differing for the number of negatively charged clusters and their location near the phosphorylation site. These differences were consistent with the charge requirements deduced from the consensus sequence of PKC and PKA substrates. A Myristyl Binding Site (MBS) was found in the PKC model between helix C and sheets 8 and 9. The identification of this MBS allowed the rationalization of the results obtained with N-myristoylated peptide inhibitors and, above all, the design of ITF1671 (H-RFARKGALRQKN-CONH-Myr), a new C-myristylamido peptide, which exerted one of the most potent inhibitory activity against PKC and PKM known to-date.
 ...
PMID:Rational design of a new C-myristylamido peptide exerting potent and selective PKC inhibitory activity. 887 44

The members of the myristoylated alanine-rich C kinase substrate (MARCKS) family are proteins essential for brain development and phagocytosis. MARCKS proteins bind to actin filaments and calmodulin (CaM) and are phosphorylated by protein kinase C. In order to investigate how these interactions are regulated, we have characterized the properties of both the myristoylated (myr) and unmyristoylated (unmyr) forms of recombinant MARCKS-related protein (MRP), a 20-kDa member of the MARCKS family. Ultracentrifugation and circular dichroic spectroscopy reveal that MRP is an elongated protein, with an axis ratio estimated between 7 and 12 and with an apparent random coil conformation. MRP binds to CaM with high affinity (Kd,myr = 4 nM; Kd,unmyr = 7 nM) and with a second order rate constant, k+1,unmyr, of 1.6 x 10(8) M-1 s-1. In contrast to classical ligands such as the myosin light chain kinase, binding of MRP to CaM does not induce the formation of an alpha-helix in MRP. The catalytic subunit of protein kinase C (PKM) phosphorylates myr MRP with high affinity ([S]0.5 = 3.5 microM), positive cooperativity (nH = 2.5) and a turnover number of 130 min-1. CaM inhibits the phosphorylation of myr MRP with a half-maximum rate of phosphorylation at a [CaM]/[MRP] ratio of 0.7, indicating that CaM might efficiently regulate the phosphorylation of MRP in vivo. Interestingly, Ca2+ inhibits the binding of MRP to CaM as well as its phosphorylation by PKM in the millimolar concentration range, suggesting that MRP has a weak affinity for Ca2+. Finally, unmyr MRP can be stoichiometrically myristoylated by N-myristoyl transferase in vitro. Since neither binding of CaM nor phosphorylation by PKM inhibits myristoylation, the N terminus of unmyr MRP is exposed on the surface of the protein and is well separated from the effector domain. In view of the observations that unmyr and myr MRP do not exhibit significant differences in their properties in solution, the function of myristoylation is most probably to modulate the interactions of MRP with membranes.
 ...
PMID:Myristoylation does not modulate the properties of MARCKS-related protein (MRP) in solution. 890 Jan 60

Spreading depression (SD) is a propagating depolarization of populations of neurons induced by intense electrical, chemical, or mechanical stimulation, which has been proposed to be an important mechanism in the aura of migraine. SD is characterized by a transient loss of synaptic transmission and thus may involve signal transduction mechanisms known to modulate synaptic strength. To examine the underlying pathophysiological molecular mechanisms of SD, we analyzed the regulation of eight protein kinase C (PKC) isoforms by immunoblot during SD induced by a high-intensity stimulus of synaptic afferents in the CA1 region of hippocampal slices. We observed a downregulation of the conventional (alpha, beta I, beta II, gamma) and the novel (delta, epsilon, eta) PKC isoforms in SD, but no change in the atypical isozyme (zeta). The coordinate downregulation of multiple PKC isoforms may be important in the functional depression of neuronal activity in SD. In contrast, the atypical zeta, and its constitutively active fragment PKM zeta, is a specific PKC isozyme that has been implicated in the maintenance of long-term potentiation (LTP) and long-term depression (LTD), widely studied models for the mechanism of memory. The stability of PKC zeta and PKM zeta in SD indicates that a molecular mechanism for the maintenance of LTP/ LTD is relatively resistant to alterations that occur during pathophysiologically large ionic fluxes. This result could help to explain the retention of information stored in the cortex despite the massive release of excitatory neurotransmitter and neuronal depolarization that may occur during the migrainous aura.
 ...
PMID:Differential downregulation of protein kinase C isoforms in spreading depression. 901 75

The interaction of urokinase-type plasminogen activator (u-PA) or of u-PA amino-terminal fragment (u-PA-ATF) with the cell surface receptor (u-PAR) was found to stimulate an increase of glucose uptake in many cell lines, ranging from normal and transformed human fibroblasts, mouse fibroblasts transfected with human u-PAR, and cells of epidermal origin. Such increase of glucose uptake reached a peak within 5-10 min, depending on the cell line, and occurred through the facilitative glucose transporters (GLUTs), since it was inhibited by cytochalasin B. Each cell line showed a specific mosaic of glucose transporter isoforms, GLUT2 being the most widespread and GLUT1 the most abundant, when present. u-PAR stimulation was followed by translocation of GLUT1 from the microsomal to the membrane compartment, as shown by both immunoblotting and immunofluorescence of sonicated plasma membrane sheets and by activation of GLUT2 on the cell surface. Both translocation and activation resulted inhibitable by protein-tyrosine kinase inhibitors and independent of downregulation of protein kinase C (PKC). The increase of intracellular glucose was followed by neosynthesis of diacylglycerol (DAG) from glucose, as previously shown. Such neosynthesis was completely inhibited by impairment of facilitative GLUT transport by cytochalasin B. DAG neosynthesis was followed by activation of PKC, whose activity translocated into the intracellular compartment (PKM), where it probably phosphorylates substrates required for u-PAR-dependent chemotaxis. Our data show that u-PAR-mediated signal transduction, related with u-PA-induced chemotaxis, involves activation of tyrosine kinase-dependent glucose transporters, leading to increased de novo DAG synthesis from glucose, eventually resulting in activation of PKC.
 ...
PMID:Interaction of urokinase-type plasminogen activator with its receptor rapidly induces activation of glucose transporters. 911 83

1. To localize protein kinase C (PKC) in the hippocampus, PKC activity measures, mRNA in situ hybridization, and [3H]phorbol ester binding techniques were used until in the 1980s antibodies became available for in situ immunocytochemistry. In the late 1980s, PKC-isoform-specific antibodies were first used to map hippocampal PKC at the cellular and subcellular level. The mammalian hippocampus contains all four Ca(2+)-dependent PKC isoforms, but the (sub)cellular localization is both isoform- and species-specific. 2. Hippocampally-dependent spatial and associative learning in rat, mice and rabbit induce an increase in PKC immunoreactivity (ir) in hippocampal principal cells studied 24 hours after the animals had learned the task. Among the four Ca(2+)-dependent PKC subtypes, this increase is selective for the gamma-isoform. The presence of the gamma-isoform in dendritic spines (the most likely site for synaptic plasticity and information storage), in contrast to PKC alpha, beta 1, and beta 2, may underlie the isoform-selectivity. 3. Compared to fully trained animals, subjects halfway training showed intermediate levels of increased PKC gamma-ir. Poor learners that were not able to learn the task showed considerably less enhanced PKC gamma-ir as compared to good learners. 4. Associative learning induced a decrease in astroglial PKC beta 2 and gamma-ir in those regions where a simultaneous increase in neuronal PKC gamma-ir was observed. This decrease most likely reflects PKC down-regulation, enabling the astrocytes to maintain their K+ buffering capacity necessary to support neuronal activity such as accompanying learning and memory. 5. Western blot analyses revealed that the increase in PKC gamma-ir was not due to an increase in total amount of PKC gamma, translocation, or the proteolytic generation of the fragment PKM. The increase in PKC gamma-ir must therefore reflect a learning-induced conformational change in the PKC gamma molecule that results in the exposure of the antigenic site(s). 6. Although a large number of hippocampal pyramidal cells display learning-induced enhancement of PKC gamma-ir at the 24 hours post-training time point, this does not indicate, however, that all synapses in these neurons are used, or that the maximal PKC signal transduction capacity per call has been reached. 7. The enhanced PKC gamma-ir may reflect a form of activated PKC, since PKC stimulation by phorbol esters (both in hippocampal slices and mildly aldehyde fixed sections) mimicked the increase in PKC gamma-ir similar as seen after learning. 8. The most likely transmitter systems which may have induced the altered PKC gamma-ir are acetylcholine and glutamate. Their contribution and interaction at the cellular level are depicted in a schematic circuit terminating on a CA1 pyramidal cell (Fig. 4). 9. Several functional roles for PKC gamma in learning and memory are discussed, and a hypothetical model is proposed based on an endogeneous PKC inhibitor protein that may explain altered antibody-binding to PKC gamma after learning (Fig. 6). 10. The immunocytochemical approach can contribute significantly to the ongoing attempts to decipher part of the cellular and biochemical mechanism of learning and memory. The development of ever more specific and better characterized antibodies reactive with different sites of proteins like PKC gamma will offer the necessary tools for further immunocytochemical research to help unravel complex brain functions.
 ...
PMID:Learning-induced alterations in hippocampal PKC-immunoreactivity: a review and hypothesis of its functional significance. 915 64

We show that, in vitro, Ca2+-dependent protein kinase C (PKC) phosphorylates recombinant murine p53 protein on several residues contained within a conserved basic region of 25 amino acids, located in the C-terminal part of the protein. Accordingly, synthetic p53-(357-381)-peptide is phosphorylated by PKC at multiple Ser and Thr residues, including Ser360, Thr365, Ser370 and Thr377. We also establish that p53-(357-381)-peptide at micromolar concentrations has the ability to stimulate sequence-specific DNA binding by p53. That stimulation is lost upon phosphorylation by PKC. To further characterise the mechanisms that regulate PKC-dependent phosphorylation of p53-(357-381)-peptide, the phosphorylation of recombinant p53 and p53-(357-381)-peptide by PKC were compared. The results suggest that phosphorylation of full-length p53 on the C-terminal PKC sites is highly dependent on the accessibility of the phosphorylation sites and that a domain on p53 distinct from p53-(357-381)-peptide is involved in binding PKC. Accordingly, we have identified a conserved 27-amino-acid peptide, p53-(320-346)-peptide, within the C-terminal region of p53 and adjacent to residues 357-381 that interacts with PKC in vitro. The interaction between p53-(320-346)-peptide and PKC inhibits PKC autophosphorylation and the phosphorylation of substrates, including p53-(357-381)-peptide, neurogranin and histone H1. Conventional Ca2+-dependent PKC alpha, beta and gamma and the catalytic fragment of PKC (PKM) were nearly equally susceptible to inhibition by p53-(320-346)-peptide. The Ca2+-independent PKC delta was much less sensitive to inhibition. The significance of these findings for understanding the in vivo phosphorylation of p53 by PKC are discussed.
 ...
PMID:The in vitro phosphorylation of p53 by calcium-dependent protein kinase C--characterization of a protein-kinase-C-binding site on p53. 918 6

In previous studies of topical application of calphostin C, a specific inhibitor of the regulatory domain of protein kinase C (PKC), and calpeptin, a selective inhibitor of calpain, to spastic canine basilar artery (BA) researchers have suggested that the catalytic fragment of PKC (known as PKM) is probably formed by a limited proteolysis of continuously activated mu-calpain, but there has been no direct evidence for PKM formation in vasospasm. The present immunoblot study with anti-PKCalpha antibody shows a significant decrease in cytosolic 80-kD PKCalpha and a concomitantly significant increase in membrane PKCalpha in the spastic canine BA. In addition, an immunoblot study in which cleavage site-directed antibodies were used demonstrated a significant increase in immunoreactive 45-kD PKM. The changes in membrane PKCalpha and PKM were enhanced with the lapse of time after subarachnoid hemorrhage. The cleavage site-directed antibodies distinguish the proteolyzed from the unproteolyzed forms of PKC for in situ analyses of enzyme regulation mediated by proteolysis. The data indicate that PKCalpha in spastic canine BA is translocated to the cell membrane, where PKCalpha is rapidly cleaved into PKM as a result of proteolysis of the isozyme by mu-calpain but not by m-calpain. The authors hypothesize that mu-calpain is continuously activated in spastic canine BA and produces PKM by limited proteolysis of PKCalpha.
 ...
PMID:Generation of the catalytic fragment of protein kinase C alpha in spastic canine basilar artery. 934 85


<< Previous 1 2 3 4 5 6 Next >>