Transcription initiation is a key point in the regulation of the expression of most genes.
The comparable complex in eukaryotes represents the minimum core for transcriptional initiation in vitro for pol II transcription. Thus, the structure of the complex will provide a detailed architectural framework for understanding the molecular mechanism of transcriptional initiation in both archaea and eukaryotes. The structure will also provide a starting point for further biochemical and genetic experiments to obtain a better understanding of the underlying regulatory mechanism.