Gene looping, defined as the interaction of the promoter and the terminator 
regions of a gene during transcription, requires transcription factor IIB 
(TFIIB). We have earlier demonstrated association of TFIIB with the distal ends 
of a gene in an activator-dependent manner (El Kaderi, B., Medler, S., 
Raghunayakula, S., and Ansari, A. (2009) J. Biol. Chem. 284, 25015-25025). The 
presence of TFIIB at the 3' end of a gene required its interaction with cleavage 
factor 1 (CF1) 3' end processing complex subunit Rna15. Here, employing affinity 
chromatography and glycerol gradient centrifugation, we show that TFIIB 
associates with poly(A) polymerase and the entire CF1 complex in yeast cells. 
The factors required for general transcription such as TATA-binding protein, RNA 
polymerase II, and TFIIH are not a component of the TFIIB complex. This 
holo-TFIIB complex was resistant to MNase digestion. The complex was observed 
only in the looping-competent strains, but not in the looping-defective sua7-1 
strain. The requirement of Rna15 in gene looping has been demonstrated earlier. 
Here we provide evidence that poly(A) polymerase (Pap1) as well as CF1 subunits 
Rna14 and Pcf11 are also required for loop formation of MET16 and INO1 genes. 
Accordingly, cross-linking of TFIIB to the 3' end of genes was abolished in the 
mutants of Pap1, Rna14, and Pcf11. We further show that in sua7-1 cells, where 
holo-TFIIB complex is not formed, the kinetics of activated transcription is 
altered. These results suggest that a complex of TFIIB, CF1 subunits, and Pap1 
exists in yeast cells. Furthermore, TFIIB interaction with the CF1 complex and 
Pap1 is crucial for gene looping and transcriptional regulation.