Isolation of the yeast INO4 gene, a positive regulator of phospholipid biosynthesis

Yeast ino4 mutants are auxotrophic for the phospholipid precursor inositol and have pleiotropic defects in phospholipid synthesis. The mutants are unable to derepress the cytoplasmic enzyme, inositol-1-phosphate synthase and they exhibit reduced synthesis of methylated phospholipids, particularly phosphatidyl-choline. The INO4 gene is believed to encode a positive regulator involved in coordinate control of phospholipid synthesis. In the present study, we report the isolation of two clones containing the INO4 gene. The clones share a region of homology and were mapped to the INO4 locus. Southern blot analysis revealed that the cloned DNA contained both unique and repetitive DNA.