A transcriptional activator protein encoded by the gal4 gene of yeast and required for the expression of genes encoding galactose-metabolizing enzymes. The GAL4 protein consists of two separable but essential domains (q.v.): an N-terminal (q.v.) domain which binds to specific DNA sequences upstream (q.v.) from the various target genes, and a C-terminal (q.v.) domain which is required to activate transcription. These properties of GAL4 have been exploited to develop the yeast two-hybrid system (q.v.) for detecting protein-protein interactions and the Drosophila targeted gene expression technique (q.v.) for studying the functioning of master control genes in various targeted tissues. See Chronology, 1989, Field and Song; 1995, Halder et al.
Subjects: Genetics and Genomics.