The propose of this study is to characterize the chromatin binding site for mineralocorticoid-receptor complexes. Very little is known about the interaction between activated receptor complexes and their chromatin targets. Our previous studies had suggested that a major binding site was found in both target and non-target tissues, and it appeared both DNA-specific and major groove-specific. These studies will be extended by identifying target cells within the kidney, enriching for these cells, and by using various chromatin probes to characterize the binding sites. As part of understanding the nature of this interaction, the structural requirements for receptor 'activation', i.e. the capacity to bind to chromatin, will also be studied.