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Phospholipid Metabolism of Wheat Grains: Phospholipid Composition and Terminal Enzymes of the CDP-Amine Phospholipid Biosynthetic Pathway

Carole L. Jelsema, D. James Morre and Manfred Ruddat
Botanical Gazette
Vol. 143, No. 1 (Mar., 1982), pp. 26-31
Stable URL: http://www.jstor.org/stable/2474375
Page Count: 6
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Phospholipid Metabolism of Wheat Grains: Phospholipid Composition and Terminal Enzymes of the CDP-Amine Phospholipid Biosynthetic Pathway
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Abstract

In aleurone layers of dry mature wheat kernels, the specific activities of the CDP-amine biosynthetic enzymes-CDP-choline: 1,2-diacylglycerol cholinephosphotransferase (E.C. 2.7.8.2.) and CDP-ethanolamine: 1,2-diacylglycerol ethanolaminephosphotransferase (E.C. 2.7.8.1.)-were low and remained so during 12 h of imbibition. Choline phosphotransferase then rose to a specific activity 14-fold that of the initial levels by 24 h of imbibition. In gibberellic acid (GA3)-treated layers, the chronology of change in enzyme activity was affected; the activity rose 6 h earlier than in controls and also decreased earlier. The specific activity of ethanolamine phosphotransferase increased twofold during the same time interval, and GA3 accelerated the changes observed during 24 h of imbibition. Protein contents of the various subcellular fractions decreased initially during imbibition but remained unchanged during GA3 treatment or within the controls, so that total activities paralleled specific activities. The major phospholipids of aleurone cells of dry mature wheat kernels were phosphatidylcholine (45%), phosphatidylglycerol (18%), phosphatidylethanolamine (12%), and phosphatidylinositol (10%). During the first 8 h of imbibition the relative contents of phosphatidylinisitol increased as phosphatidylglycerol decreased. The increase was pronounced with GA3 treatment.

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