The objectives of this proposal are four-fold. First, we will construct and characterize bacterial plasmid vectors which can be used to efficiently clone regions of DNA involved in the promotion and termination of transcription. These specialized vectors, called promoter-probe and terminator-probe plasmid vectors, will be thoroughly characterized with respect to their ability to clone known promoter/terminator sequences as well as those which have not yet been identified. Secondly, these vectors will be used to isolate and characterize promoter and terminator sequences from a variety of organisms, including eukaryotes. Thirdly, we plan to use this experimental approach to better understand the protein/DNA interactions associated with the control of gene expression at the level of transcription. This approach will be augmented by the generation of promoter and terminator mutations. This will enable us to determine which nucleotides or arrangements of nucleotides are involved in these functions. Finally we hope to determine whether prokaryotic regulatory structures and mechanisms are present and functional in eukaryotes.