The de novo biosynthesis of platelet-activating factor in rat brain.
Platelet-Activating Factor (PAF, 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is present in nervous tissue and its function is still unknown. We have demonstrated that rat brain is able to synthesize PAF from 1-alkyl-2-acetyl-sn-glycerol and CDP-choline by a "DTT-insensitive" phosphocholine transferase. This represents the last step of the de novo pathway which apparently is the only one existing in the brain for PAF biosynthesis. The enzyme has a microsomal localization, requires Mg++ and is inhibited by Ca++ as reported for phosphocholine transferase utilizing long-chain diradylglycerols as substrates. However, other properties of PAF-synthesizing enzyme (sensitivity to DTT and dependence on pH) are different from those of phosphocholine transferase responsible for the synthesis of diacyl and long-chain alkylacyl glycerophosphocholines. These observations indicate that a specific enzyme for PAF biosynthesis might exist in rat brain.
Francescangeli
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Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università di Perugia, Italy.
Goracci
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G
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002798:Diacylglycerol Cholinephosphotransferase / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D008274:Magnesium; D008861:Microsomes / Q000201:enzymology; D010713:Phosphatidylcholines; D010972:Platelet Activating Factor / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000378:metabolism; D013379:Substrate Specificity
D010713:Phosphatidylcholines; D010972:Platelet Activating Factor; C044819:1,2-diarachidonoyl-glycero-3-phosphocholine; D002798:Diacylglycerol Cholinephosphotransferase; D008274:Magnesium; D004229:Dithiothreitol