Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rat skeletal muscle calpastatin form is markedly modified in its inhibitory properties by means of a reverse reaction which involves both phosphorylation and dephosphorylation. Dephospho-calpastatin shows greater inhibitory efficiency versus mu-calpain, whereas phospho-calpastatin shows maximal inhibition versus m-calpain. Both forms are present in fresh rat muscle. Phosphorylation has been reproduced "in vitro" using a homologous Ca2+ independent protein kinase and found to result in the incorporation of approximately one mole of 32P per mole of protein. Dephosphorylation was induced by treatment with alkaline phosphatase and 32P release shown found to correlate with modifications of the inhibitory properties. This reversible covalent modification of calpastatin is considered an important advancement in the understanding of how different calpain isoforms can be more efficiently controlled by a single inhibitor isozyme form.
...
PMID:Modulation of inhibitory efficiency of rat skeletal muscle calpastatin by phosphorylation. 153 Jun 32

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.
...
PMID:Specific degradation of troponin T and I by mu-calpain and its modulation by substrate phosphorylation. 775 88

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.
...
PMID:Modulation of calpastatin specificity in rat tissues by reversible phosphorylation and dephosphorylation. 814 76

Isolated connexin-32s from rat and mouse liver are proteolyzed in vitro by the intracellular Ca(2+)-dependent neutral proteases, mu-calpain and m-calpain, producing a major fragment of 26 kDa. Connexin-26 is not proteolyzed by calpain. Calpain cleaves connexin-32 at its C-terminal end as shown by 125I-calmodulin binding experiments. Connexin-32, but not connexin-26, is phosphorylated by both protein kinase A and protein kinase C in serine residues and the sites of phosphorylation by both kinases remain in the major 26-kDa fragment resulting from calpain proteolysis. Phosphorylation of connexin-32 by protein kinase C, but not by protein kinase A, prevents the proteolytic attack of mu-calpain and m-calpain. Phosphorylation of connexin-32 by protein kinase A and protein kinase C does not prevent its proteolysis by papain, alpha-chymotrypsin, proteinase K, and trypsin.
...
PMID:Phosphorylation of connexin-32 by protein kinase C prevents its proteolysis by mu-calpain and m-calpain. 839 Sep 88

Phosphorylation by adenosine-3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA), but not by Ca(++)-calmodulin-dependent protein kinase II (CaMK II), was shown earlier to protect microtubule-associated protein 2 (MAP2) from cleavage by m-calpain (Johnson and Foley: J Neurosci Res 34: 642-647, 1993). We reinvestigated this phenomenon with the physiologically more relevant mu-calpain and found a qualitatively similar but quantitatively different picture. We further demonstrate that 1) protection is biphasically dependent on the degree of phosphorylation; 2) Ca(++)-phospholipid-dependent protein kinase (PKC) has about the same effect as PKA; 3) the effects of kinases A and C are not additive; and 4) stripping of native MAP2 from its phosphate content (17.8 +/- 2.3 mol/mol) enhances calpainolysis 3.6-fold. A reciprocal effect between kinase A and MAP2 was found: the RII, but not the RI, regulatory subunit of kinase A, which was shown to bind specifically to MAP2, is protected by MAP2 from mu-calpain attack. It is suggested that the specific anchoring of kinase A-II on MAP2 may serve not only kinase targeting in the dendrites, but also protection from calpainolytic degradation.
...
PMID:Mutual protection of microtubule-associated protein 2 (MAP2) and cyclic AMP-dependent protein kinase II against mu-calpain. 877 65

Calpain (calcium-activated neutral protease) has been implicated as playing a role of neuronal injury in cerebral ischemia and excitotoxicity. Here we report that, in addition to extreme excitotoxic conditions [N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and kainate challenges], other neurotoxins such as maitotoxin, A23187, and okadaic acid also induce calpain activation, as detected by m-calpain autolytic fragmentation and nonerythroid alpha-spectrin breakdown. Under the same conditions, calmodulin-dependent protein kinase II-alpha (CaMPK-IIalpha) and neuronal nitric oxide synthase (nNOS) are both proteolytically cleaved by calpain. Such fragmentation can be reduced by calpain inhibitors (acetyl-Leu-Leu-Nle-CHO and PD151746). In vitro digestion of protein extract from cortical cultures with purified mu- and m-calpain produced fragmentation patterns for CaMPK-IIalpha and nNOS similar to those produced in situ. Also, several other calpain-sensitive calmodulin-binding proteins (plasma membrane calcium pump, microtubule-associated protein 2, and calcineurin A) and protein kinase C-alpha are also degraded in neurotoxin-treated cultures. Lastly, in a rat pup model of acute excitotoxicity, intrastriatal injection of NMDA resulted in breakdown of CaMPK-IIalpha and nNOS. The degradation of CaMPK-IIalpha, nNOS, and other endogenous calpain substrates may contribute to the neuronal injury associated with various neurotoxins.
...
PMID:Neuronal nitric oxide synthase and calmodulin-dependent protein kinase IIalpha undergo neurotoxin-induced proteolysis. 928 22

Myristoyl-CoA:protein N-myristoyltransferase (NMT) catalyzes the attachment of myristate onto the amino terminal glycine residue of select polypeptides. Cardiac tissue expresses high levels of cAMP-dependent protein kinase whose catalytic subunit is myristoylated; however, cardiac muscle extracts were found to contain low NMT activities. Northern blot analysis of bovine heart poly(A)+ RNA probed with bovine spleen NMT cDNA revealed a 1.7-kb mRNA. Western blot analysis of cardiac muscle extracts with human NMT antibody indicated a prominent immunoreactive band with a molecular mass of 50 kDa. The expression of mRNA and protein levels in cardiac muscle is not correlated with NMT activities, suggesting the presence of regulators of the enzyme activity. We have isolated the cDNA encoding bovine cardiac muscle NMT (cNMT) by reverse transcription polymerase chain reaction. The single long open reading frame of 1248 bp of bovine cNMT specifies a protein of 416 amino acids with a predicted mass of 46,686 Da. The cDNA clone expressed in Escherichia coli resulted in the production of functionally active 50-kDa NMT. Ultrastructural and immunolocalization of NMT utilizing the immunogold labeling technique demonstrated cytoplasmic distribution with occasional mitochondrial and myofilaments localization of the NMT antibody. Cardiac muscle NMT has a higher affinity for myristoyl-CoA than toward palmitoyl-CoA. Substrate specificity indicated that cNMT has a higher affinity toward pp60src and M2 gene segment of reovirus type 3-derived peptide substrates than toward cAMP-dependent protein kinase-derived peptide. Primary translational product of cNMT sequence contained several regions rich in proline, glutamic acid, serine, and threonine, which are known as "PEST" regions. PEST-FIND analysis of the amino acid sequences indicated eight PEST regions were present in the cNMT. These PEST regions are suggested to be recognized by specific proteases, particularly Ca(2+)-dependent neutral proteases, calpains, which are responsible for the degradation of PEST-containing proteins. We have demonstrated the abolishment of NMT activity and NMT protein degradation in vitro by m-calpain. The proteolysis of cNMT by m-calpain and the abolishment of NMT activity was prevented by the calpain inhibitor, calpastatin. These observations indicate that calpains may regulate NMT activity.
...
PMID:Myristoyl-coA:protein N-myristoyltransferase from bovine cardiac muscle: molecular cloning, kinetic analysis, and in vitro proteolytic cleavage by m-calpain. 963 10

We have shown previously that the ELR-negative CXC chemokines interferon-inducible protein 10, monokine induced by gamma interferon, and platelet factor 4 inhibit epidermal growth factor (EGF)-induced m-calpain activation and thereby EGF-induced fibroblast cell motility (H. Shiraha, A. Glading, K. Gupta, and A. Wells, J. Cell Biol. 146:243-253, 1999). However, how this cross attenuation could be accomplished remained unknown since the molecular basis of physiological m-calpain regulation is unknown. As the initial operative attenuation signal from the CXCR3 receptor was cyclic AMP (cAMP), we verified that this second messenger blocked EGF-induced motility of fibroblasts (55% +/- 4.5% inhibition) by preventing rear release during active locomotion. EGF-induced calpain activation was inhibited by cAMP activation of protein kinase A (PKA), as the PKA inhibitors H-89 and Rp-8Br-cAMPS abrogated cAMP inhibition of both motility and calpain activation. We hypothesized that PKA might negatively modulate m-calpain in an unexpected manner by directly phosphorylating m-calpain. A mutant human large subunit of m-calpain was genetically engineered to negate a putative PKA consensus sequence in the regulatory domain III (ST369/370AA) and was expressed in NR6WT mouse fibroblasts to represent about 30% of total m-calpain in these cells. This construct was not phosphorylated by PKA in vitro while a wild-type construct was, providing proof of the principle that m-calpain can be directly phosphorylated by PKA at this site. cAMP suppressed EGF-induced calpain activity of cells overexpressing a control wild-type human m-calpain (83% +/- 3.7% inhibition) but only marginally suppressed that of cells expressing the PKA-resistant mutant human m-calpain (25% +/- 5.5% inhibition). The EGF-induced motility of the cells expressing the PKA-resistant mutant also was not inhibited by cAMP. Structural modeling revealed that new constraints resulting from phosphorylation at serine 369 would restrict domain movement and help "freeze" m-calpain in an inactive state. These data point to a novel mechanism of negative control of calpain activation, direct phosphorylation by PKA.
...
PMID:Activation of m-calpain (calpain II) by epidermal growth factor is limited by protein kinase A phosphorylation of m-calpain. 1190 64

Accumulating evidence indicates that calpains can reside in or translocate to the cell nucleus, but their functions in this compartment remain poorly understood. Dissociated cultures of cerebellar granule cells (GCs) demonstrate improved long-term survival when their growth medium is supplemented with depolarizing agents that stimulate Ca(2+) influx and activate calmodulin-dependent signaling cascades, notably 20 mm KCl. We previously observed Ca(2+)-dependent down-regulation of Ca(2+)/calmodulin-dependent protein kinase (CaMK) type IV, which was attenuated by calpain inhibitors, in GCs supplemented with 20 mm KCl (Tremper-Wells, B., Mathur, A., Beaman-Hall, C. M., and Vallano, M. L. (2002) J. Neurochem. 81, 314-324). CaMKIV is highly enriched in the nucleus and thought to be critical for improved survival. Here, we demonstrate by immunolocalization/confocal microscopy and subcellular fractionation that the regulatory and catalytic subunits of m-calpain are enriched in GC nuclei, including GCs grown in medium containing 5 mm KCl. Calpain-mediated proteolysis of CaMKIV is selective, as several other nuclear and non-nuclear calpain substrates were not degraded under chronic depolarizing culture conditions. Depolarization and Ca(2+)-dependent down-regulation of CaMKIV were associated with significant alterations in other components of the Ca(2+)-CaMKIV signaling cascade: the ratio of phosphorylated to total cAMP response element-binding protein (a downstream CaMKIV substrate) was reduced by approximately 10-fold, and the amount of CaMK kinase (an upstream activator of CaMKIV) protein and mRNA was significantly reduced. We hypothesize that calpain-mediated CaMKIV proteolysis is an autoregulatory feedback response to sustained activation of a Ca(2+)-CaMKIV signaling pathway, resulting from growth of cultures in medium containing 25 mm KCl. This study establishes nuclear m-calpain as a regulator of CaMKIV and associated signaling molecules under conditions of sustained Ca(2+) influx.
...
PMID:Nuclear calpain regulates Ca2+-dependent signaling via proteolysis of nuclear Ca2+/calmodulin-dependent protein kinase type IV in cultured neurons. 1553 35

Angiogenesis plays a critical role in wound repair. Endothelial cells present CXC receptor 3 (CXCR3) for chemokines expressed late in wound regeneration. To understand the physiological role CXCR3 plays in regulating endothelial function, we analyzed the ability of a CXCR3 ligand, IP-10 (CXCL10), to influence endothelial cell tube formation. Treatment of endothelial cells with IP-10 in the presence of vascular endothelial growth factor (VEGF) inhibited tube formation on growth factor-reduced Matrigel and in a subcutaneous Matrigel plug. Furthermore, IP-10 significantly inhibited VEGF-induced endothelial motility, a response critical for angiogenesis. Previous work showed that CXCR3 ligandation initiates protein kinase A (PKA) phosphorylation-dependent inhibition of m-calpain, required for induced cell motility, in fibroblasts but not epithelial cells. Here we show that CXCR3 activation in endothelial cells induces an increase in cAMP and PKA activation. Treatment of endothelial cells with Rp-8-Br-cAMP, an inhibitor of PKA, or small interference RNA to PKA was able to reverse the inhibitory effects of IP-10 on VEGF-mediated tube formation and motility. Importantly, treatment of endothelial cells with VEGF induced the activation of m-calpain, but costimulation with IP-10 significantly decreased this activity. Using Rp-8-Br-cAMP, we show blocking PKA reversed the IP-10 inhibition of VEGF-induced m-calpain activity. These data indicate that the activation of CXCR3 inhibits endothelial tube formation through a PKA mediated inhibition of m-calpain. This provides a means by which late wound repair signals limit the angiogenesis driven early in the wound response process.
...
PMID:IP-10 blocks vascular endothelial growth factor-induced endothelial cell motility and tube formation via inhibition of calpain. 1648 16


1 2 3 Next >>

---