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)

A protein of 80 kDa apparent molecular mass was found to be specifically myristolylated in rat brain cytosols derived from either whole brain or synaptosomes. The attachment of the fatty acid took place in the absence of protein synthesis, since the cytosols did not incorporate [14C]lysine into protein, nor did cycloheximide affect the incorporation of the myristic acid into the protein. The fatty acid was incorporated into the protein via an acid-labile/alkali-resistant band, and Pronase digestion of the labelled protein showed that the lipid was covalently linked to a glycine residue. Together, these data suggested that the myristic acid was amide-linked to the N-terminal residue of the protein. The protein was identified as one of the major protein kinase C substrates, the MARCKS (myristoylated alanine-rich C kinase substrate) protein, by showing that Ca2+ stimulated its phosphorylation, by its heat stability and by immune precipitation (using an antiserum to the MARCKS protein). Incorporation of myristic acid into intact protein continued for up to 12 h, despite the fact that over this period some degradation of the protein could be demonstrated. In pulse-chase experiments, the pattern of loss of the incorporated fatty acid was similar to that of the protein itself, and therefore the loss of radioactivity probably reflects protein degradation rather than specific de-acylation of the protein. Together, these results suggest that there is a pool of unacylated MARCKS protein in the rat brain.
 ...
PMID:Evidence for a non-myristoylated pool of the 80 kDa protein kinase C substrate of rat brain. 224 73

CaVPT, a target protein of Ca2(+)-vector from amphioxus muscle, was purified from its complex with CaVP after dissociation by 6 M urea and chromatographies on DEAE-cellulose and calmodulin-Sepharose. The amino acid sequence of CaVPT has been determined. The protein is composed of 243 residues and possesses an unblocked N terminus. Its molecular weight is 26,621, distinctly lower than the apparent molecular weight deduced from electrophoresis on sodium dodecyl sulfate-containing gels. CaVPT contains a potential Asn-linked glycosylation site, four potential protein kinase C phosphorylation sites, and two casein kinase II phosphorylation sites. From the sequence the following three particular domains can be inferred: a collagen-like N-terminal segment, rich in Pro and Ala, that resembles the N-terminal segment of skeletal muscle myosin light chain kinase; next to it (from residues 33 to 50) is located a strongly amphiphilic and basic alpha-helical segment which likely binds the calcium vector protein since a proteolytic cut after Arg50, occurring occasionally during the purification of CaVPT, impairs the binding to immobilized calmodulin. This segment is followed by two immunoglobulin folds. The two immunoglobulin folds typically belong to the C2 subclass and particularly resemble those present in the neural cell surface adhesion molecules NCAM, L1, F11, MAG, TAG-1, fasciclin II, and amalgam. Recently, the presence of immunoglobulin folds of this type has been reported in some intracellular muscular proteins, namely in smooth muscle myosin light chain kinase, striated muscle C protein and titin, as well as in the nematode 600-kDa protein twitchin. From this structural study we can formulate the working hypothesis that CaVPT acts on the structure of the thick filament in muscle or regulates, perhaps via other immunoglobulin fold-containing proteins.
 ...
PMID:Primary structure of the target of calcium vector protein of amphioxus. 224 56

Protein kinase C is maintained in an inactive state by the action of an inhibitory region within the effector binding domain of the kinase. It has been suggested that a short stretch of amino acids (pseudosubstrate site) mediates this inhibition by binding to the active site and preventing substrate interaction [House, C. and Kemp, B. E. (1987) Science 238, 1726-1728]. A mutated version of protein kinase C-alpha containing a glutamic acid for alanine substitution in this region has been analysed for biochemical properties and biological function. Consistent with the importance of this pseudosubstrate site in regulating kinase activity, this altered protein has a significantly increased effector-independent kinase activity relative to wild-type protein kinase C-alpha and shows increased sensitivity to activation by proteolysis. The increased activity of this protein in the intact cell was confirmed by its ability to stimulate expression from a phorbol-ester-inducible reporter construct in a transient transfection system. Expression of a mutant kinase with the pseudosubstrate sequence deleted causes greater induction in this transient expression system, consistent with this kinase being independent of effectors and thus constitutively active.
 ...
PMID:Mutagenesis of the pseudosubstrate site of protein kinase C leads to activation. 225 27

The complete primary structure has been determined for an inhibitor protein of protein kinase C. The bovine brain-derived inhibitor has a pI of 6 and its N-terminal alanine residue is blocked by acetylation. Fragments obtained by chemical and enzymatic cleavage of the purified inhibitor were analyzed by Edman degradation, fast atom bombardment mass spectrometry, and tandem mass spectrometry. The results establish that the protein has a calculated average molecular mass of 13,690 daltons and contains 125 amino acid residues with the following sequence: (sequence: see text) The inhibitor does not show significant homology with any other known protein. Circular dichroism of the freshly prepared apoprotein indicated a secondary structural content of 23% alpha-helix, 31% beta-sheet, and 11% beta-turn. Immobilization on nitrocellulose followed by exposure to a 65Zn2(+)-containing overlay solution showed that, like protein kinase C itself, the inhibitor is a zinc-binding protein, although the sequence does not reveal a "zinc finger" structure. Competition with 10-fold molar excess Ca2+ or Mg2+ did not reduce the zinc-binding specificity of this inhibitor.
 ...
PMID:Amino acid sequence and characterization of a protein inhibitor of protein kinase C. 230 77

The localization of MARCKS (myristoylated, alanine-rich C-kinase substrate), a major specific substrate for protein kinase C, has been studied in the rat brain. Light microscopic immunocytochemistry and biochemical analysis demonstrated that the protein is widespread throughout the brain and enriched in certain regions, including the piriform and entorhinal cortices, portions of the amygdaloid complex, the intralaminar thalamic nuclei, the hypothalamus, the nucleus of the solitary tract, nucleus ambiguus, and many catecholaminergic and serotonergic nuclei. Electron microscopic analysis revealed immunoreactivity in axons, axon terminals, small dendritic branches, and occasionally in dendritic spines. In neuronal processes, immunoreactivity was particularly prominent in association with microtubules, but reaction product was also seen in cytosol and adjacent to plasma membranes. No reaction product was observed in large dendrites, somata, or nuclei. A population of strongly immunoreactive glial cells was also observed. Many of these glial cells were morphologically similar to microglial cells, although some resembled astrocytes. In glial cells, both cytoplasm and plasma membranes were heavily labeled. The distribution of the MARCKS protein did not coincide precisely with the distribution of any of the subspecies of protein kinase C. The results indicate that the MARCKS protein is expressed in the majority of cell types in the CNS, and they suggest that the protein may be involved both in glial cell functions and in neuronal functions involving cytoskeletal elements in small dendritic branches and axon terminals.
 ...
PMID:Localization of the MARCKS (87 kDa) protein, a major specific substrate for protein kinase C, in rat brain. 233 3

Activation of protein kinase C (PKC) in human T lymphocytes is an immediate consequence of mitogenic signalling via the antigen-receptor complex and CD2 antigen. In order to investigate further the signal-transduction pathways which result in PKC activation, we have established a novel PKC assay system using streptolysin-O-permeabilized T cells. Known peptide substrates of PKC were introduced into permeabilized cells in the presence of [gamma-32P]ATP, 3 mM-Mg2+ and 150 nM free Ca2+. The peptide found to have the lowest background phosphorylation had the sequence Pro-Leu-Ser-Arg-Thr-Leu-Ser-Val-Ala-Ala-Lys-Lys (peptide GS), and the phosphorylation of the peptide was increased up to 6-fold by direct activation of PKC with phorbol 12,13-dibutyrate. Induction of PKC activation with the UCHT1 antibody against the CD3 antigen, or with phytohaemagglutinin (PHA) or guanosine 5'-[gamma-thio]triphosphate (GTP[S]), increased peptide-GS phosphorylation by 2-3 fold. The specificity of PKC action on peptide GS was demonstrated by blocking increases in phosphorylation with a pseudosubstrate peptide PKC inhibitor. PKC activation by this technique could be detected within 1 min of adding external ligand. Dose-response curves revealed that PHA-induced production of inositol phosphates correlated closely with PKC activities, whereas only a partial correlation between these parameters was observed with GTP[S]. Our data are consistent with the presence of more than one G-protein-mediated pathway of PKC regulation in T cells. The quantitative PKC assay system described is both simple and reproducible, and its potential application to a wide range of cell types should prove useful in further investigations of PKC activation mechanisms.
 ...
PMID:A method for measuring protein kinase C activity in permeabilized T lymphocytes by using peptide substrates. Evidence for multiple pathways of kinase activation. 236 76

Magainins are a family of antimicrobial peptides present in the skin extracts of Xenopus laevis. Both magainin-1 and -2 do not have any significant effect on the activity of protein kinase C (PKC). Magainin-2 was found to be readily phosphorylated by PKC to 0.5 mol 32P/mol of peptide. Neither magainin-1, which has a sequence of S8AGK and not S8AKK as in the case of magainin-2, nor the magainin-2 analogue with substitution of Ala for Ser8 was phosphorylated by the kinase, suggesting that Ser8 is the phosphorylation site of magainin-2. One synthetic analogue of magainin, designated magainin B, which has a greater tendency for alpha-helix formation in non-aqueous environment than the parent peptide resulting from substitution of Ser8, Gly13, and Gly18 with Ala in magainin-2-amide, is a potent inhibitor of PKC. This peptide inhibits all three PKC isozymes with IC50 less than 20 microM. Magainin B also inhibits the binding of [3H]phorbol 12,13-dibutyrate to the kinase. These results suggest that magainin-2 may be modified by PKC through phosphorylation and that certain synthetic analogues of magainins may be used as inhibitors of PKC.
 ...
PMID:Phosphorylation of magainin-2 by protein kinase C and inhibition of protein kinase C isozymes by a synthetic analogue of magainin-2-amide. 236 80

A structure-function study of the protein kinase C (PK-C) pseudosubstrate sequence (R19FARK-GALRQKNV31) has been undertaken. The role of specific residues was investigated using an alanine substitution scan. Arg-22 was the most important determinant in the inhibitor sequence, since substitution of this residue by alanine gave a 600-fold increase in the IC50 value to 81 +/- 9 microM. Substitutions of other basic residue also increased the IC50, 5-, 11- and 24-fold for the Ala-19, Ala-23 and Ala-27 substitutions, respectively. The importance of basic residues in determining the potency of the pseudosubstrate peptide reflects the requirements for these residues in peptide substrate phosphorylation. The residues Gly-24, Leu-26 and Gln-28 were also important for pseudosubstrate inhibitor potency. The large difference in the IC50 value for the [A22]PK-C(19-31) peptide makes it a valuable control in studies employing the pseudosubstrate peptide to explore functional roles of PK-C.
 ...
PMID:Protein kinase C pseudosubstrate prototope: structure-function relationships. 240 Jun 34

The substrate specificity of phospholipid/Ca2+-dependent protein kinase (protein kinase C) was studied using synthetic peptides, in particular those corresponding to the amino acid sequence around serine 115 in bovine myelin basic protein (MBP). It was found that MBP (104-118) and MBP (104-123) were substrates for the enzyme, with apparent Km values of 14 and 10 microM, respectively. Neither MBP (111-118) nor MBP (111-123) were phosphorylated, indicating that an additional segment of sequence extending toward the N terminus, but not toward the C terminus, was essential for the substrate activity of the peptides. Of the alanine-substituted analogs examined, [Ala 105] MBP (104-118) was comparable to the parent peptide, whereas [Ala 107] MBP (104-118) and [Ala 113] MBP-(104-118) were much poorer substrates. These findings indicated that lysine 105 was not essential, but both arginine 107 and arginine 113 were important specificity determinants. Initial studies revealed that [Ala 113] MBP (104-118) inhibited phosphorylation by the enzyme of the parent peptide and, to a lesser extent, the intact MBP(1-170). Serine 115 was the only site phosphorylated in the analog peptides [Ala 105] MBP (104-118) and [Ala 107]MBP (104-118). In the parent peptide, serine 115 was the initial site of phosphorylation but after prolonged phosphorylation other sites became phosphorylated (serine 110 and/or serine 112), further supporting the concept that arginine residues act as essential substrate specificity determinants for phospholipid/Ca2+-dependent protein kinase.
 ...
PMID:Substrate specificity of phospholipid/Ca2+-dependent protein kinase as probed with synthetic peptide fragments of the bovine myelin basic protein. 241 12

Synthetic peptide analogs of the bovine myelin basic protein (MBP) corresponding to residues 104-118 were found to specifically inhibit phospholipid/ Ca2+-dependent protein kinase (protein kinase C). The peptides [Ala107]MBP (104-118) and [Ala113]MBP (104-118) inhibited protein phosphorylation of intact MBP, histone H1 and peptide phosphorylation with MBP(104-123), MBP(104-118) or [Ala105]MBP (104-118) as substrates. The inhibitor peptides [Ala107]MBP(104-118) and [Ala113]MBP (104-118), containing alanine in place of the arginine recognition sites, apparently inhibited the enzyme noncompetitively with respect to substrates, with IC50 values ranging from 46-145 and 28-62 microM, respectively. These peptide analogs did not inhibit cyclic AMP-dependent protein kinase or myosin light chain kinase but inhibited phospholipid/Ca2+-dependent phosphorylation of endogenous proteins in the total, solubilized fraction of rat brain.
 ...
PMID:Synthetic myelin basic protein peptide analogs are specific inhibitors of phospholipid/calcium-dependent protein kinase (protein kinase C). 241 28


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