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)

Protein-tyrosine kinase activities have appeared so far to be intrinsic for two classes of proteins: the transforming proteins of certain retroviral oncogenes and the membrane receptors for certain cellular growth factors. In this latter family, the protein-tyrosine kinase is activated upon binding of the growth factor to its receptor and phosphorylates both the receptor itself and other cell target proteins. Growth factor receptors are transmembrane glycoproteins able to undergo not only autophosphorylation but also phosphorylation by other protein kinases (e.g., protein kinase C). Both autophosphorylation and heterologous phosphorylation of the receptor are regulatory events for the ligand binding and protein-tyrosine kinase intrinsic activities of the growth factor receptors.
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PMID:Membrane receptors with protein-tyrosine kinase activity. 282 May 17

Five protein kinases are shown to serve as specific phosphatases in the absence of ADP. Although the rates of hydrolysis are very slow compared to the forward phosphorylation rates under optimal conditions, they are of the same order as the reverse reaction in the presence of ADP. Because cells contain approximately equal to 3 mM ATP, neither the reverse reaction nor the phosphatase is likely to play a physiological role. beta-casein B phosphorylated by the catalytic subunit of cAMP-dependent protein kinase (protein kinase A) is specifically dephosphorylated by protein kinase A but not by polypeptide-dependent protein kinase (protein kinase P). beta-casein B phosphorylated by protein kinase P is specifically dephosphorylated by protein kinase P but not by protein kinase A. Histone H1 phosphorylated by protein kinase C is dephosphorylated by the same enzyme in the absence of ADP. In all cases tested addition of ADP and F1-ATPase accelerates moderately the rate of dephosphorylation. Native H+-ATPase from yeast plasma membranes is isolated mainly in the phosphorylated form. It is dephosphorylated and rephosphorylated by protein kinase P but not by protein kinase A. Protein-tyrosine kinase of the epidermal growth factor receptor phosphorylates the random synthetic polypeptide poly(Glu80Tyr20). The phosphorylated polymer is specifically dephosphorylated in the absence of ADP by epidermal growth factor receptor preparations but not by insulin receptor preparations. The same polymer phosphorylated by insulin receptor is dephosphorylated by insulin receptor but not by epidermal growth factor receptor preparations. By using a cycle of dephosphorylation-rephosphorylation, it is possible to identify proteins that are phosphorylated by these protein kinases in vivo. Should this method be applicable to additional protein kinases, it should be possible to estimate the quantitative contribution of each protein kinase to a single phosphoprotein.
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PMID:Specific dephosphorylation of phosphoproteins by protein-serine and -tyrosine kinases. 290 Oct 92

Long-term depression (LTD) at the parallel fiber-Purkinje cell synapse in the cerebellum is a well-known example of synaptic plasticity. Although LTD is thought to reflect an enduring loss of postsynaptic AMPA receptor sensitivity, the underlying mechanisms are unclear. Protein-tyrosine kinases (PTKs) are able to modulate ionotropic receptor function and are enriched in Purkinje cells. Using intracellular recording from Purkinje cells, it is shown that two structurally and mechanistically distinct PTK inhibitors, lavendustin A and herbimycin A, block LTD induced by pairing parallel fiber stimulation with postsynaptic Ca2+ spiking. Intracellular application of the protein kinase C (PKC) activator, (-)-indolactam V, consistently depressed parallel fiber-Purkinje cells EPSPs and occluded pairing-induced LTD. Herbimycin A nullified the run-down produced by (-)-indolactam V. These data suggest that PTKs are necessary for LTD at the parallel fiber-Purkinje cell synapse and that PKC-induced synaptic depression requires PTK activity.
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PMID:Tyrosine kinase is required for long-term depression in the cerebellum. 860 98

Phospholipase D2 (PLD2) is expressed in brain and inhibited by synuclein, which is involved in Parkinson's and Alzheimer's diseases. However, the activation mechanism of PLD2 in neuronal cells has not been defined clearly. Hydrogen peroxide (H(2)O(2)) plays roles in the neurodegenerative diseases and also acts as a second messenger of various molecules such as nerve growth factor. To study regulation mechanisms of PLD2 by H(2)O(2) in neuronal cells, we have made stable PC12 cell lines expressing PLD2 (PLD2-PC12 cells). H(2)O(2) treatment stimulated PLD activity in PLD2-PC12 cells in a dose- and time-dependent manner. This activation was inhibited by the treatment with protein kinase C (PKC) inhibitors or by depletion of PKCalpha, -delta, and -epsilon. Phorbol ester markedly activated PLD2. Co-treatment with phorbol ester and H(2)O(2) did not show an additive effect. Chelation of extracellular calcium substantially blocked the H(2)O(2)-induced activation of PLD2. A calcium ionophore induced PLD2 activation in a PKC-dependent manner. Protein-tyrosine kinase inhibitors inhibited H(2)O(2)-induced PLD activation slightly. These data indicate that H(2)O(2) can activate PLD2 in PC12 cells and that this activation is largely dependent on PKC and Ca(2+) ions and minimally dependent on tyrosine phosphorylation.
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PMID:Regulation of phospholipase D2 by H(2)O(2) in PC12 cells. 1108 Jan 96