Effects of rhTRF2 and flag⋅hTRF2–TFIIA on transcription by
RNA polymerase III. (A) Transcription of the
7SK gene. System C contained 1.5 and 10 μl of
fractions cEDF 1 M and cEDF 0.2 M, respectively, prepared as described
in Materials and Methods and 24 ng of a rhTFIIIB
component (TFIIIB150) related to Saccharomyces
cerevisiae TFIIIB90 (M.T., Z.W., M. Ito, K. H. Seifart, and
R.G.R., unpublished data). Individual lanes were supplemented with the
following transcription factors. Lane 1: none; lanes 2 and 3: 20 and 40
ng of rhTBP; lanes 4–6 and 9–11: 20, 40, and 80 ng of rhTRF2,
respectively; lanes 7 and 8 and 12 and 13: 20 and 40 ng of flag-tagged
human TRF2, complexed with TFIIA (approximately 80 and 160 ng of
protein in total); lanes 9–13 contained, in addition, 40 ng of rhTBP.
(B) Transcription of the VAI gene. System
D contained 0.5 μl of core TFIIIC purified from cell line Cβ (37),
0.1 μl of core RNA polymerase III purified from cell line BN51 (38),
150 ng of rhPC4 (21), 6 ng of rhTFIIIB150 (M.T., Z.W., M. Ito, K. H.
Seifart, and R.G.R., unpublished data), and 6 ng of rhTFIIIB90 (4).
Other additions were as follows: 5 ng of rhTBP in lanes 1–5; 6 ng of
rhTFIIA in lanes 2, 5, 7, and 10; 6 ng of rhTRF2 in lanes 3, 5, 8, and
10; and 24 ng of purified flag⋅hTRF2–TFIIA complex (6 ng
flag⋅hTRF2) in lanes 4 and 9.