FIGURE 2.

Sedimentation analysis of TFIIB. A, sedimentation analysis reveals copurification of CF1 subunits and poly(A) polymerase with TFIIB. Affinity-purified HA-tagged TFIIB was subjected to sedimentation analysis in 5–30% (v/v) glycerol gradient in 150 mm KCl. Fractions of 1.8 ml each were collected and subjected to SDS-PAGE analysis followed by Western blotting to visualize TFIIB, CF1 subunits, and poly(A) polymerase. Input bands indicate affinity-purified sample prior to sedimentation analysis. B, sedimentation analysis of affinity-purified TFIIB from wild type cells, rTFIIB, and affinity-purified TFIIB from looping-defective sua7-1 cells under the conditions as described above.