MANY eukaryotic proteins involved in transcriptional regulation contain within their DNA-binding domains a polypeptide loop (the zinc finger) which interacts with DNA1,2. In proteins possessing multiple zinc fingers, including TFIIIA3, Spl4,5, SWI56 and oestrogen/glucocorticoid receptors7, the region containing the zinc fingers confers DNA-binding specificity. By contrast, our results demonstrate that all but one of the 28 amino acids encompassing the single zinc-finger region of GAL4, the yeast transcriptional activator, can be replaced with the analogous zinc-finger region from another yeast-activator protein, PPR1, without changing the DNA-binding specificity of GAL4. A 14-amino-acid region adjacent to the zinc finger is necessary for determining specific recognition of DNA sequences.
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