The overall goal of this research is to elucidate mechanisms that regulate genetic expression at the levels of transcription and RNA processing and to understand the importance of these mechanisms for B lymphocyte development and ribosome biogenesis. Studies of immunoglobulin gene regulation in the mouse will include (i) analysis of the parameters governing the regulation of heavy chain mRNA production by alternative RNA processing, (ii) characterization of a novel V(kappa) gene promoter element and its cognate transcription factor, (iii) an attempt to define the roles of intronic and downstream enhancers for the establishment and maintenance of kappa gene transcription, and (iv) an exploration of immunoglobulin gene regulation in FACS-fractionated populations of B lymphoid cells. Studies of mouse ribosomal protein genes will include (i) characterization of the factors that recognize the distinctive promoters of these genes and cloning of the factor-encoding genes, (ii) elucidation of interactions between the various promoter elements, and (iii) a study of the importance of intron splicing for the stabilization and efficient intracellular transpose of mRNA.