| Modification Notes |
The GAL4 protein of Saccharomyces cerevisiae is one of the most thoroughly characterized transcriptional activators. Since the N-terminal 147 amino acid residues of GAL4 are sufficient to mediate specific and strong binding to DNA, but are incapable of efficient transcriptional activation, this protein fragment has frequently been used to confer specific DNA binding in experiments examining transcriptional activation functions of heterologous proteins. This approach is facilitated by the finding that higher eukaryotes lack endogenous proteins that enhance transcription from the consensus GAL4-binding site. The transcriptional activation (TA) domain, which corresponds to C-terminal amino acids 768-881, facilitates the activation of GAL genes, such as GAL1, GAL2, GAL7, GAL10 and MEL1, in response to galactose. Fusions between GAL4 (an amino acid sequence) and activating domains from a variety of transcriptional regulatory proteins can activate transcription in yeast, plant, insects and mammalian cells. A unique “two-hybrid” system has been developed using GAL4 fusions in yeast to identify specific protein-protein interactions. |
