This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (18) Citing Articles via Google Scholar Google Scholar Articles by Sparace, S. A. Articles by Moore, T. S. Search for Related Content PubMed PubMed Citation Articles by Sparace, S. A. Articles by Moore, T. S., Jr. Agricola Articles by Sparace, S. A. Articles by Moore, T. S.

Articles

Phospholipid Metabolism in Plant Mitochondria

II. SUBMITOCHONDRIAL SITES OF SYNTHESIS OF PHOSPHATIDYLCHOLINE AND PHOSPHATIDYLETHANOLAMINE ¹

Department of Botany, University of Wyoming, Laramie, Wyoming 82071

CDPcholine:1,2-diacylglycerol cholinephosphotransferase (EC 2.7.8.2) and CDPethanolamine:1,2-diacylglycerol ethanolaminephosphotransferase (EC 2.7.8.1) were detected in mitochondrial fractions from castor bean (Ricinus communis) endosperm. These activities were not due to contamination of the fractions with endoplasmic reticulum. The enzymes were localized on both the inner and outer mitochondrial membranes.

Only minor kinetic differences between the phosphatidylcholine-synthesizing activities of intact mitochondria and of the endoplasmic reticulum were found. The K_m of the mitochondrial enzyme for CDP-choline was about 2 units less than that for the enzyme of the endoplasmic reticulum (8.0 and 10.0 micromolar, respectively). The mitochondrial enzyme activity was maximal above 10 millimolar Mg²⁺, whereas maximum endoplasmic reticulum activity was achieved by 4 millimolar. The endoplasmic reticulum enzyme was more stable at 37 C than was that of the mitochondria. The mitochondrial cholinephosphotransferase represented about 1 to 2% of the total activity isolated from castor bean endosperm.

This article has been cited by other articles:

				A. Nerlich, M. von Orlow, D. Rontein, A. D. Hanson, and P. Dormann Deficiency in Phosphatidylserine Decarboxylase Activity in the psd1 psd2 psd3 Triple Mutant of Arabidopsis Affects Phosphatidylethanolamine Accumulation in Mitochondria Plant Physiology, June 1, 2007; 144(2): 904 - 914. [Abstract] [Full Text] [PDF]