Primary structure of the Saccharomyces cerevisiae GAL4 gene.

The GAL4 gene encodes a positive regulator of the galactose-inducible genes in Saccharomyces cerevisiae. Recently, GAL4 has been cloned and its 2.8-kilobase mRNA has been identified. We report here the DNA sequence of GAL4 and the mapping of the 5' and 3' ends of its transcripts. The region sequenced contains a single open reading frame, 881 codons long, which could encode a 99,350-dalton protein. The 5' ends of the GAL4 transcripts fall into two clusters. Transcripts which begin at the upstream cluster would encode the 99,350-dalton protein, whereas those starting at the downstream cluster may result in the synthesis of a shorter, 91,600-dalton protein. The putative GAL4 proteins contain an amino acid sequence near their amino termini which resembles a DNA-binding motif found in bacterial and phage repressors and gene activator proteins.