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SCIENCE AT THE EDGE SEMINAR QB/GEDD Friday, February 18 at 11:30am Room 1400 Biomedical and Physical Sciences Bldg. Refreshments at 11:15 Joan Conaway Stowers Institute for Medical Research, Kansas City, MO The Mediator of RNA Polymerase II Transcription: Links to Transcription Elongation and Leukemogenesis Promoter proximal pausing by initiated RNA polymerase II (Pol II) and regulated release of paused polymerase into productive elongation has emerged as a major mechanism of transcription activation. Reactivation of paused Pol II has been shown to correlate with recruitment of a so-called Super-Elongation Complex or SEC that contains the transcription elongation factors ELL/EAF and P-TEFb, as well as a collection of additional proteins encoded by genes involved in translocations with the MLL gene in leukemia. Our lab has recently obtained evidence for a role of human Mediator in recruiting SEC and another ELL/EAF-containing complex to genes. I will present evidence that a conserved N-terminal domain in the Mediator subunit Med26 provides docking sites for ELL/EAF, P-TEFb, and associated proteins as well as the general initiation factor TFIID. In addition, I will present evidence consistent with the model that Med26 may function as a molecular switch that interacts first with the Pol II initiation complex through direct interactions with TFIID and then "exchanges" TFIID for complexes containing elongation factors ELL/EAF and P-TEFb to facilitate the transition of Pol II into the elongation stage of transcription. Helen Geiger Administrative Assistant Quantitative Biology Graduate Program/ Gene Expression in Development & Disease Michigan State University 502B Biochemistry Building East Lansing, MI 48824 Phone: (517) 432-9895 Fax: (517) 353-9334 E-mail: [log in to unmask]<mailto:[log in to unmask]> Web: http://qbmi.msu.edu<http://qbmi.msu.edu/> http://www.bch.msu.edu/GEDD/index.htm<http://www.bch.msu.edu/GEDD/MSU-TRSB-Symposium.htm>