Sequence Homology of the Yeast Regulatory Protein ADR1 with Xenopus Transcription Factor TFIIIA

Classical yeast genetics coupled with the cloning of regulatory genes by complementation of function is a powerful means of identifying and isolating trans-acting regulatory elements. One such regulatory gene is ADR1 which encodes a protein required for transcriptional activation of the glucose-repressible alcohol dehydrogenase (ADH2) gene. We now report the nucleotide sequence of ADR1; it encodes a polypeptide chain of 1,323 amino acids, of which the amino-terminal 302 amino acids are sufficient to stimulate ADH2 transcription. This active amino-terminal region shows amino-acid sequence homology with the repetitive DNA-binding domain of TFIIIA, an RNA polymerase III transcription factor of Xenopus laevis. Similar domains are found in proteins encoded at the Krüppel and Serendipity loci of Drosophila melanogaster. We discuss the implications of this structural homology and suggest that a similar domain may exist in other yeast regulatory proteins such as those encoded by GAL4 (ref. 13) and PPR1 (ref.14).