Transcription of yeast phospholipid biosynthesis structural genes, which contain an inositol-sensitive upstream activa-ting sequence in their promoters, responds to the availability of the soluble precursors inositol and choline and to changes in phospholipid metabolism. The INO1gene is deregulated (derepressedwhen inositol ispresent)under the conditionsof increased phosphatidylcholine (PtdCho) turnover, as occurs in the sec14Dcki1Dstrain (SEC14encodes the major yeast phosphatidylinositol transfer protein;CKI1encodes choline kinase of the cytidine diphosphate choline pathway of PtdCho biosynthesis). .
