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. 1972 Sep;69(9):2429–2432. doi: 10.1073/pnas.69.9.2429

Intracellular Distribution of Enzymes of the Cytidine Diphosphate Choline Pathway in Castor Bean Endosperm

J M Lord 1, T Kagawa 1, Harry Beevers 1
PMCID: PMC426957  PMID: 4506764

Abstract

The occurrence and subcellular distribution of enzymes of the cytidine diphosphate choline pathway of lecithin synthesis have been examined. Choline kinase (EC 2.7.1.32) was completely soluble, while phosphorylcholine-cytidyl transferase (EC 2.7.7.15) and phosphorylcholine-glyceride transferase (EC 2.7.8.2) were associated with particulate fractions. Although components sedimenting at 10,000 to 100,000 × g contained both enzymes, phosphorylcholine-cytidyl transferase and particularly phosphorylcholine-glyceride transferase were present in the 10,000 × g pellet, which contained the major organelles, mitochondria, and glyoxysomes. When the crude homogenate was centrifuged on a sucrose density gradient, four major bands of particulate protein were recovered. A band at density 1.24 g/cm3 contained the glyoxysomes and was devoid of phosphorylcholine-cytidyl transferase and phosphorylcholine-glyceride transferase activity. Enzyme activity was barely detectable in the mitochondria, at density 1.18 g/cm2. Phosphorylcholine-glyceride transferase was found almost exclusively in a sharp band at density 1.12 g/cm3, and phosphorylcholinecytidyl transferase was found in the uppermost band at density 1.08 g/cm3. Thus, for the synthesis of lecithin in their membranes, the glyoxysomes and mitochondria depend on enzymes elsewhere in the cell; the final two steps in lecithin formation occur, apparently exclusively, in separate particulate cell components.

Keywords: lecithin, membranes, glyoxysomes, mitochondria, endoplasmic reticulum

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. BORKENHAGEN L. F., KENNEDY E. P. The enzymatic synthesis of cytidine diphosphate choline. J Biol Chem. 1957 Aug;227(2):951–962. [PubMed] [Google Scholar]
  2. Bracker C. E., Grove S. N. Continuity between cytoplasmic endomembranes and outer mitochondrial membranes in fungi. Protoplasma. 1971;73(1):15–34. doi: 10.1007/BF01286408. [DOI] [PubMed] [Google Scholar]
  3. Franke W. W., Kartenbeck J. Outer mitochondrial membrane continuous with endoplasmic reticulum. Protoplasma. 1971;73(1):35–41. doi: 10.1007/BF01286409. [DOI] [PubMed] [Google Scholar]
  4. Johnson K. D., Kende H. Hormonal Control of Lecithin Synthesis in Barley Aleurone Cells: Regulation of the CDP-Choline Pathway by Gibberellin. Proc Natl Acad Sci U S A. 1971 Nov;68(11):2674–2677. doi: 10.1073/pnas.68.11.2674. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Jungalwala F. B., Dawson R. M. Phospholipid synthesis and exchange in isolated liver cells. Biochem J. 1970 Apr;117(3):481–490. doi: 10.1042/bj1170481. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Jungalwala F. B., Dawson R. M. The origin of mitochondrial phosphatidylcholine within the liver cell. Eur J Biochem. 1970 Feb;12(2):399–402. doi: 10.1111/j.1432-1033.1970.tb00865.x. [DOI] [PubMed] [Google Scholar]
  7. KENNEDY E. P. Biosynthesis of phospholipides. Fed Proc. 1957 Sep;16(3):847–853. [PubMed] [Google Scholar]
  8. Kaiser W., Bygrave F. L. Incorporation of choline into the outer and inner membranes of isolated rat liver mitochondria. Eur J Biochem. 1968 May;4(4):582–585. doi: 10.1111/j.1432-1033.1968.tb00253.x. [DOI] [PubMed] [Google Scholar]
  9. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  10. McCaman R. E., Cook K. Intermediary metabolism of phospholipids in brain tissue. 3. Phosphocholine-glyceride transferase. J Biol Chem. 1966 Jul 25;241(14):3390–3394. [PubMed] [Google Scholar]
  11. McMurray W. C., Dawson R. M. Phospholipid exchange reactions within the liver cell. Biochem J. 1969 Mar;112(1):91–108. doi: 10.1042/bj1120091. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Morré D. J., Merritt W. D., Lembi C. A. Connections between mitochondria and endoplasmic reticulum in rat liver and onion stem. Protoplasma. 1971;73(1):43–49. doi: 10.1007/BF01286410. [DOI] [PubMed] [Google Scholar]
  13. Morré D. J., Nyquist S., Rivera E. Lecithin Biosynthetic Enzymes of Onion Stem and the Distribution of Phosphorylcholine-Cytidyl Transferase among Cell Fractions. Plant Physiol. 1970 Jun;45(6):800–804. doi: 10.1104/pp.45.6.800. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. PHILLIPS A. H., LANGDON R. G. Hepatic triphosphopyridine nucleotide-cytochrome c reductase: isolation, characterization, and kinetic studies. J Biol Chem. 1962 Aug;237:2652–2660. [PubMed] [Google Scholar]
  15. Ruby J. R., Dyer R. F., Skalko R. G. Continuities between mitochondria and endoplasmic reticulum in the mammalian ovary. Z Zellforsch Mikrosk Anat. 1969;97(1):30–37. doi: 10.1007/BF00331868. [DOI] [PubMed] [Google Scholar]
  16. SCHNEIDER W. C. INTRACELLULAR DISTRIBUTION OF ENZYMES. XIII. ENZYMATIC SYNTHESIS OF DEOXYCYTIDINE DIPHOSPHATE CHOLINE AND LECITHIN IN RAT LIVER. J Biol Chem. 1963 Nov;238:3572–3578. [PubMed] [Google Scholar]
  17. Stoffel W., Schiefer H. G. Biosynthesis and composition of phosphatides in outer and inner mitochondrial membranes. Hoppe Seylers Z Physiol Chem. 1968 Aug;349(8):1017–1026. doi: 10.1515/bchm2.1968.349.2.1017. [DOI] [PubMed] [Google Scholar]
  18. Tanaka K., Tolbert N. E., Gohlke A. F. Choline kinase and phosphorylcholine phosphatase in plants. Plant Physiol. 1966 Feb;41(2):307–312. doi: 10.1104/pp.41.2.307. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. WEISS S. B., SMITH S. W., KENNEDY E. P. The enzymatic formation of lecithin from cytidine diphosphate choline and D-1,2-diglyceride. J Biol Chem. 1958 Mar;231(1):53–64. [PubMed] [Google Scholar]
  20. WILGRAM G. F., KENNEDY E. P. INTRACELLULAR DISTRIBUTION OF SOME ENZYMES CATALYZING REACTIONS IN THE BIOSYNTHESIS OF COMPLEX LIPIDS. J Biol Chem. 1963 Aug;238:2615–2619. [PubMed] [Google Scholar]

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