Transcription Factor II: A Structure with Multiple Functions

The process of transcription, by which RNA is read from DNA, is executed by a large complex of 40 to 50 proteins. The crystal structure of three molecules at the core of this complex is presented by Geiger et al. (p. 830) in this issue of Science . In their Perspective, Jacobson and Tjian explain why the resolution of this structure is an important step on the road to understanding the entire transcription machinery.