The nucleic acid/protein interactions that are important in the transcriptional activation of 5S rRNA genes will be characterized in detail. The specific questions to be addressed are of considerable interest in the broader context of eukaryotic gene expression and regulation. These studies focus on the Xenopus transcription factor 111A (TF 111A) with the internal control region (ICR) of 5S rRNA genes. The structural aspects of TF111A that are important in sequence specific DNA and RNA binding as well as in transcriptional activation will be analyzed using directed mutagenesis techniques to produce structurally altered TF111A variants. A saturated set of point mutations will be created in the 5S ICR. A major goal in the analysis of eukaryotic gene structure and function is to understand the mechanisms whereby a specific gene is transcriptionally activated, and how these mechanisms contribute to genetic regulation. It has become clear that questions relating to transcriptional mechanism and regulation can now be restated in biochemical terms. Such answers will be sought by Dr. Setzer.