Updated project metadata. Although TFIIB is widely regarded as an initiation factor, recent reports have implicated it in multiple aspects of eukaryotic transcription. To investigate the broader role of TFIIB in transcription, we performed quantitative proteomic analysis of yeast TFIIB. We purified two different populations of TFIIB; one form soluble cell lysate, which is not engaged in transcription, and the other from chromatin fraction which yields the transcriptionally active form of the protein. TFIIB purified from the chromatin exhibits several interactions that explain its non-canonical roles in transcription. RNAPII, TFIIF and TFIIH were the only components of preinitiation complex with a significant presence in chromatin TFIIB. A notable feature was the substantial enrichment of all 3’ end processing-termination factors; CF1, CPF and Rat1 in chromatin-TFIIB preparation. These results corroborate the role of TFIIB in termination of transcription. Presence of the Lsm complex as well as TREX complex subunit Sub2 in chromatin-TFIIB opens the possibility of novel roles of TFIIB in synthesis-decay coupling and nucleocytoplasmic transport of mRNA. This multiplicity of functions may contribute to the preferential targeting of TFIIB during viral pathogenesis