The promoter of the yeast OPI1 regulatory gene.

In Saccharomyces cerevisiae, the expression of several genes encoding enzymes involved in lipid metabolism is regulated by inositol and choline. The transcriptional heterodimeric complex composed of the gene products of INO2 and INO4 binds to a conserved cis-acting upstream activating sequence designated as the inositol-choline responsive element (ICRE), and activates the expression of these genes. In the presence of inositol and choline, the expression of these genes is downregulated and a functional OPI1 gene product is necessary for this repression.