Cytidylyltransferase translocation onto endoplasmic reticulum and increased de novo synthesis without phosphatidylcholine accumulation in Krebs-II ascite cells
| Autor: | Gérard Ribbes, Chap Hugues, François Tercé, Michel Record, Hélène Tronchère |
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| Rok vydání: | 1991 |
| Předmět: |
Cytidylyltransferase
Biophysics Phospholipid Oleic Acids Biology Endoplasmic Reticulum Biochemistry Choline Carcinoma Krebs 2 chemistry.chemical_compound Cytosol Endocrinology Phosphatidylcholine Tumor Cells Cultured Animals Choline-Phosphate Cytidylyltransferase Phospholipids chemistry.chemical_classification Dose-Response Relationship Drug Endoplasmic reticulum Cell Membrane Fatty acid Nucleotidyltransferases De novo synthesis Oleic acid chemistry Phosphatidylcholines Oleic Acid |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism. 1084:69-77 |
| ISSN: | 0005-2760 |
| Popis: | Addition of oleic acid to Krebs-II cells stimulated by 9-fold [3H]choline incorporation into choline glycerophospholipids without affecting the selective incorporation of the precursor into diacyl subclass (90% of total [3H]choline glycerophospholipids). The total activity of cytidylyltransferase (E.C. 2.7.7.15), the regulatory enzyme of choline glycerophospholipid synthesis, was increased in the particulate fraction at the expense of cytosol. Free [3H]oleic acid was also associated with the particulate fraction. Subcellular fractionation of membranes on Percoll gradient, indicated that the endoplasmic reticulum, which contained 90% of total cell free oleic acid, was the unique target for the translocation of cytidylyltransferase. [3H]oleic acid was incorporated almost exclusively into phosphatidylcholine and corresponded to a synthesis of 9 nmol/h per 106 cells. Based on [3H]choline incorporation a net synthesis of 22 nmol/h per 106 cells was determined. However, oleic acid treatment did not change the total amount of phosphatidylcholine (45 nmol/106 cells) and other phospholipids; also no modification in the subcellular distribution of phospholipids was observed. It is concluded that the stimulation of the de novo synthesis of phosphatidylcholine which involves translocation of cytidylyltransferase onto the endoplasmic reticulum, is accompanied by a renewal of their polar head group. Also exogenous oleic acid induces an enhanced fatty acid turnover, highly specific for phosphatidylcholine. Therefore, Krebs-II cells exhibited a high degree of regulation of their phosphatidylcholine content, suggesting a parallel stimulation of both synthesis and degradation. |
| Databáze: | OpenAIRE |
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