Two transcription factors, Gln3p and Nil1p, use the same GATAAG sites to activate the expression of GAP1 of Saccharomyces cerevisiae.

We present an analysis of the DNA region located upstream of GAP1, the structural gene for the general amino acid permease, which contains the sites required for activation of transcription of this gene in response to the nitrogen source of the growth medium. This gene is not expressed in media containing glutamine, and its transcription is activated in response to Gln3p in cells using glutamate as the source of nitrogen and by Nil1p in cells using urea as the source of nitrogen. We show that full response to both activators requires the presence of two GATAAG sites, as well as the presence of auxiliary sites located in the interval between 602 and 453 bp from the translational start site. The fact that both Gln3p and Nil1p utilize GATAAG sites to activate transcription is reflected in the high homology of the zinc finger regions of the two proteins.