Fig. 3.

Reinitiation properties of all-rTFIIIB. PICs were assembled for 30 min on tDNA^Ile(TAT) (Upper) or tDNA^Gly(TCC) (Lower) by using TFIIIC and different types of reconstituted TFIIIB. In lanes 1–8 and 17–24, TFIIIB was reconstituted from rTBP and rBrf1 proteins plus crude B′′. In lanes 9–16 and 25–32, pure rBdp1 protein from insect cells (100 ng) was used instead of B′′. Pol III (10 ng) was then added together with an NTP mixture lacking CTP, and the incubation was continued for 15 min. Transcription was resumed by the addition of CTP, either in the presence or in the absence of heparin, and the incubation continued for the indicated times. The ratios between the amounts of single- and multiple-round transcription products (MR/SR) are reported below the lanes.