title: Calcium- and phospholipid-dependent protein kinase C and phosphatidylinositol kinase: two major phosphorylation systems in the cornea.
abstract: The signaling messengers for the regulation of intracellular calcium-dependent functions involve a phospholipid-sensitive protein kinase (protein kinase C) modulated by diacylglycerol, which is a product of phosphoinositide degradation. We found that protein kinase C activity is two times higher in the epithelium than in the stroma-endothelial layers of the rabbit cornea. 12-0-tetradecanoylphorbol-13-acetate (TPA) and phosphatidylserine stimulate protein kinase C at low Ca2+ concentrations. The TPA-phosphatidylserine stimulated activity of corneal epithelium was recovered in the soluble fraction; in the membrane-bound fraction, a very active phosphatidylinositol kinase accounted for half the basal phosphorylation of the corneal epithelium.
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D019870:1-Phosphatidylinositol 4-Kinase; D000818:Animals; D003315:Cornea / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004533:Egtazic Acid / Q000494:pharmacology; D004848:Epithelium / Q000201:enzymology; D007546:Isoquinolines / Q000494:pharmacology; D010718:Phosphatidylserines / Q000494:pharmacology; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011817:Rabbits; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D007546:Isoquinolines; D010718:Phosphatidylserines; D010879:Piperazines; D004533:Egtazic Acid; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate