The long-range goal of this work is to understand the basic molecular mechanisms of gene regulation, both in procaryotic and eucaryotic cells. Primarily, DNA-binding proteins will be studied. The E. coli lac repressor and the cyclic AMP-dependent catabolite gene activator protein will be studied in detail. Methods for the fractionation, isolation, and characterization of DNA binding proteins will be perfected and applied to both procaryotic and eucaryotic cells.