The expression of a very large number of genes (mostly glycolytic genes or translational component genes) that influence the growth rate of the budding yeast Saccharomyces cerevisiae is influenced in turn by the action of only a few regulatory proteins. In a recent publication we presented evidence that two of these regulatory proteins, TUF and GCR, activate transcription interdependently. Our data suggested that GCR is an absolute requirement for activation by a single, isolated TUF binding site (UASrpg element). Here we propose to test the reciprocal idea- that UASrpg is an absolute requirement for activation by GCR. We will try to disprove the idea that GCR-dependent transcriptional activation occurs only through UASrpg, and test for DNA binding by the GCR protein. The successful completion of this research will contribute to our understanding of GCR function, and form the basis for further investigation of the complex roles of TUF, how those roles are balanced in vivo, and the means by which growth rate is controlled in yeast cells. Yeast cells respond to changes in their environment (e.g., availability of nutrients) by changing their rate of growth and division. These changes involve the complex coordination of the action of many different genes in the cell. The mechanism of this coordination is poorly understood, and this is a proposal to study one aspect of this process.