Elevated phosphocholine concentration in ras-transformed NIH 3T3 cells arises from increased choline kinase activity, not from phosphatidylcholine breakdown.
The cellular concentration of phosphocholine has been reported to be significantly elevated in Ha-ras-transformed NIH 3T3 cells, but not in v-sis transformants (J. C. Lacal, J. Moscat, and S. A. Aaronson, Nature [London] 330:269-271, 1987). It was suggested that the phosphocholine arises from constitutive hydrolysis of phosphatidylcholine by phospholipase C, an activity that would also account for the elevated 1,2-diacylglycerol found in ras-transformed cells. I have demonstrated that the increased phosphocholine arises through the induction of choline kinase activity. No increased breakdown of phosphatidylcholine was observed in ras-transformed cells. The elevation in diacylglycerol is therefore unlikely to be a consequence of phosphatidylinositol or phosphatidylcholine turnover.
Macara
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IG
Department of Biophysics, University of Rochester Medical Center, New York 14642.
D002461:Cell Line, Transformed; D002478:Cells, Cultured; D002797:Choline Kinase / Q000378:metabolism*; D005347:Fibroblasts / Q000201:enzymology; D011905:Genes, ras; D007700:Kinetics; D010713:Phosphatidylcholines / Q000032:analysis* / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism*; D014316:Tritium
D010713:Phosphatidylcholines; D014316:Tritium; D010770:Phosphotransferases; D002797:Choline Kinase