Regulation of the ilv 1 multifunctional gene in Saccharomyces cerevisiae.

The ilv 1 gene in S. cerevisiae codes for a regulatory protein involved in depression of the ilv 2 and ilv 3 genes as well as a biosynthetic enzyme, threonine deaminase. 2. The ilv 1 gene does not autogenously regulate its catalytic product threonine deaninase. 3. Regulation of the ilv 2 and ilv 3 gene products involve different aporepressors than regulation of the ilv 1 gene product. 4. The ilv I multifunctional gene in S. cerevisiae may be a duplication and fusion of a bacterial like ilv 1 gene where ilv 1 catalytic and regulatory function have been differentially conserved.