RNA polymerase III transcription in the yeast Saccharomyces cerevisiae.

The yeast RNA polymerase III system is probably the best-characterized eukaryotic transcription system. Nearly all of the components have been identified and the genes for them cloned. Many of the interactions within initiation complexes are coming to light. Considering the many parallels between Pol III transcription and the other polymerase systems, findings in the Pol III system can act as predictions for Pol II and Pol I transcription. Despite the many advances made in the study of transcription by RNA polymerase III, many important questions remain to be answered. It is unclear what are the functions of individual TFIIIC, TFIIIB and polymerase subunits. Why are so many proteins required? Another extremely important mystery is the mechanism by which the factors assemble. What is the molecular mechanism for TFIIIC recruiting TFIIIB, and how does TFIIIB recruit polymerase? These and many other problems will eventually be solved as researchers apply the biochemical and genetic techniques available in the yeast system.