Tyrosine phosphorylation and activation of PKC and its role in celluar regulation

PKC，其中comprises a family of ten isoforms， is activated by 1，2-diacylglycerol produced from receptor-mediated hydrolysis of inositol phospholipids. On the other贪污,PKC isoforms be indicated to be tyrosine phosphorylated in response to the treatment ofcells with hydrogen peroxide (h2o). Among the PKC isoforms，PKCδ is efficiently tyrosine phosphorylated and catalytically activated. In this study，phosphorylation-dependent activation of PKCδ was分析。Firstly，intracellular localization of PKCδ was observed under confocal microscope by monitoring thefluorescence of the GFP-fusion protein of PKCδ. the GFP-fusion protein was translocated to themembrane by the stimuli generating 1,2 -diacylglycerol，whereas the fusion protein did not move in the H D22 D22 D22 D2-treated cells. Therefore，PKCδ was concluded to be activated by H D22 D2O D22 D2 in a manner independent of the membranetranslocation induced by 1,2 -dia…cyglycerol. It is well known that H D22 D2O D22 D22 D2 suppresses the protein-tyrosinephosphatase reaction and thus increase类型phosphorylation of various cellular proteins。Several protein-tyrosine phosphatase inhibitors, howeverdid not induce类型phosphorylation of PKCδ，indicating activation of protein-tyrosine kinase rather than inhibition of protein-tyrosinephosphatase is necessary for the covalent modification of PKCδ. Phosphotyrosine residuesthe study of a series of mutant protein of PKCδ and by the mass spectrometric analysisof the phosphopetides of PKCδ recovered from the H - 22 - D2O - D22 -treated cells. Three tyrosineresidues were identified， and体外phosphorylation of these tyrosine residues by Lck，a non-receptor type protein-tyrosine kinaseactivated the enzyme. Activation of PKCδ by tyrosine phosphorylation was detected even三个小时after the H D22 D2O D22 D2 treatment，因此，积极的激活可能有一个重要的角色在long-term responses of the cells to theextracellular stimuli. Less

It has been shown that PKC, which comprises a family of ten isoforms, is activated by 1, 2-diacylglycerol produced from receptor-mediated hydrolysis of inositol phospholipids. On the other hand, the PKC isoforms have been indicated to be tyrosine phosphorylated in response to the treatment of cells with hydrogen peroxide (HィイD22ィエD2OィイD22ィエD2). Among the PKC isoforms, PKCδ is efficiently tyrosine phosphorylated and catalytically activated. In this study, phosphorylation-dependent activation of PKCδ was analyzed. Firstly, the intracellular localization of PKCδ was observed under confocal microscope by monitoring the fluorescence of the GFP-fusion protein of PKCδ. The GFP-fusion protein was translocated to the membrane by the stimuli generating 1, 2-diacylglycerol, whereas the fusion protein did not move in the HィイD22ィエD2OィイD22ィエD2-treated cells. Therefore, PKCδ was concluded to be activated by HィイD22ィエD2OィイD22ィエD2 in a manner independent of the membrane translocation induced by 1, 2-dia … More cyglycerol. It is well known that HィイD22ィエD2OィイD22ィエD2 suppresses the protein-tyrosine phosphatase reaction and thus increase tyrosine phosphorylation of various cellular proteins. Several protein-tyrosine phosphatase inhibitors, however, did not induce tyrosine phosphorylation of PKCδ, indicating that activation of protein-tyrosine kinase rather than inhibition of protein-tyrosine phosphatase is necessary for the covalent modification of PKCδ. Phosphotyrosine residues were determined by the study of a series of mutant protein of PKCδ and by the mass spectrometric analysis of the phosphopetides of PKCδ recovered from the HィイD22ィエD2OィイD22ィエD2-treated cells. Three tyrosine residues were identified, and in vitro phosphorylation of these tyrosine residues by Lck, a non-receptor type protein-tyrosine kinase, activated the enzyme. Activation of PKCδ by tyrosine phosphorylation was detected even three hours after the HィイD22ィエD2OィイD22ィエD2 treatment, and thus the active enzyme may have an important role in the long-term responses of the cells to the extracellular stimuli. Less