Distinct effects of phosphatidylethanol on three types of rat brain protein kinase C.
Protein kinase C plays a crucial role in signal transduction for activating cellular function. Phosphatidylserine and Ca2+ are essential for the activation of protein kinase C, and diacylglycerol which is produced in the receptor-mediated hydrolysis of inositol phospholipids, increases the affinity of this enzyme for phosphatidylserine and Ca2+. In brain tissues, protein kinase C has been shown to be separated into three fractions, Type I, II, and III by hydroxyapatite column chromatography, and cDNA analysis has revealed that they correspond to gamma-, beta I-, beta II-, and alpha-cDNA, respectively. Phospholipase D has been known to catalyze the transphosphatidyl reaction between various membrane phospholipids and alcohols. In fact, phosphatidylethanol has been found in many tissues including brain of ethanol-treated rats. This report describes the different responses of three distinct forms of protein kinase C to phosphatidylethanol. Phosphatidylethanol can replace phosphatidylserine at high Ca2+ concentrations for the activation of Type I, II, and III protein kinase C. However, phosphatidylethanol can activate only Type I enzyme at physiological Ca2+ concentrations, which is expressed exclusively in the central nervous tissue. Consideration of these results suggests the possibility that ethanol may exert some effect on the signal transduction in neuronal tissue, via changes in protein phosphorylation.
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D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D020404:Glycerophospholipids; D010712:Phosphatidic Acids / Q000378:metabolism*; D010718:Phosphatidylserines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats
D020404:Glycerophospholipids; D010712:Phosphatidic Acids; D010718:Phosphatidylserines; D010743:Phospholipids; C051521:phosphatidylethanol; D011493:Protein Kinase C; D002118:Calcium