Cellular Regulation of Phospholipid Biosynthesis

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Science  11 Jun 2004:
Vol. 304, Issue 5677, pp. 1561
DOI: 10.1126/science.304.5677.1561f

How do cells homeostatically regulate the lipid composition of their membranes? Phospholipid metabolism in yeast is coordinately repressed by the transcription factor Opi1p, which in turn is activated by extracellular inositol. Loewen et al. (p. 1644) now show that there is a pool of phosphatidic acid (PA) on the endoplasmic reticulum (ER) that is highly sensitive to growth conditions, in particular to the presence of exogenous inositol. This PA is directly sensed by the soluble transcriptional repressor Opi1p, which binds to PA in the ER and prevents it from entering the nucleus and altering transcription. When inositol is restored to cells, the Opi1p-associated PA is metabolized, which releases the Opi1p from the ER and allowing its entry into the nucleus.”

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