TFIIB binds to YY1. (A) TFIIB binds to
YY1 in solution. Purified TFIIB and YY1 were subjected to gel
filtration chromatography alone or after mixing, and localized in the
elution profile by protein blot assay using polyclonal antibody (18) to
YY1 (Top), TFIIB (Middle), or a mixture
of the antibodies (Bottom). Chymotrypsinogen A
(25 kDa), BSA (68 kDa), and β-galactosidase (120 kDa) were markers.
(B) TFIIB binds to GST–YY1. TFIIB was monitored by protein
blot assay. Lanes: IN, TFIIB input to each reaction; NB, TFIIB not
bound; NaCl, TFIIB eluted in buffer containing 1.0 M NaCl; EG, TFIIB
eluted in buffer containing 50% ethylene glycol plus 100 mM NaCl; SDS,
TFIIB eluted by boiling in buffer with detergent, either immediately
after application to the affinity matrix (lanes 1 and 9) or following
elution with ethylene glycol (lane 7); YY1, TFIIB eluted in buffer
containing 60 μg/ml YY1. (C) Copurification of TFIIB and
YY1 from a HeLa cell nuclear extract. Two fractions from a
single-stranded DNA cellulose column (0.3 M and 0.6 M NaCl) containing
both YY1 and TFIIB were assayed on a YY1-specific IgG matrix. TFIIB and
YY1 were detected by protein blot assay. Lanes: IN, TFIIB and YY1 input
to each reaction; NB, input which is not bound; B, input which is
bound; PRE, input bound by preimmune IgG. Figures were produced using
photoshop and freehand software.