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Previous studies have shown that transcription factors IIB (TFIIB), IIF (TFIIF), and RNA polymerase II (RNAPII) play important roles in determining the position of mRNA 5'-ends in the yeast Saccharomyces cerevisiae. Yeast strains containing a deletion of the small, nonessential Rpb9 subunit of RNAPII exhibit an upstream shift in the positions of mRNA 5'-ends, whereas mutation of the large subunit of yeast TFIIF (Tfg1) can suppress downstream shifts that are conferred by mutations in TFIIB. In this study, we report an approach for the production of functional recombinant yeast boloTFIIF (Tfg1-Tfg2 complex) and use of the recombinant protein in both reconstitute 1 transcription assays and gel mobility shifts in order to investigate the biochemical alterations associated with the ΔRpb9 polymerase. The results demonstrated that upstream shifts in the positions of mRNA 5'-ends could be conferred by the ΔRpb9 RNAPII in transcription reactions reconstituted with highly purified yeast general transcription factors and, importantly, that these shifts are associated with an impaired interaction between the ΔRpb9 polymerase and TFIIF. Potential mechanisms by which an altered interaction between the ΔRpb9 RNAPII and TFIIF confers an upstream shift in the positions of mRNA 5'-ends are discussed. [ABSTRACT FROM AUTHOR]