The UGA35 gene of Saccharomyces cerevisiae (also called DURL) encodes a positive regulator of the expression of structural genes involved in 4-aminobutyric acid (GABA) and urea catabolisms. The UGA35 gene has been cloned by complementation of function and identified by chromosomal gene replacement. The sequence of this regulatory gene and its flanking regions has been established. Our data reveal an open reading frame of 2892 nt, corresponding to 964 amino acids (aa). The deduced UGA35 aa sequence shares several similarities with that of other regulatory proteins, suggesting that the UGA35 gene encodes a DNA-binding transcriptional activator. We also show that UGA35 and the DAL81 regulatory gene controlling allantoin and urea catabolisms are one and the same gene. This means that the same factor is required for specific induction of three distinct catabolic pathways, namely those involved in GABA, urea and allantoin utilization as nitrogen sources.