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Figure 3.
Putative DNA binding surface and electrostatic potential
surface properties of tTFIIB[C] compared to human TFIIB[C]. (A)
The putative DNA binding face of tTFIIB[C] (Left) reveals a more
neutral surface than the highly basic DNA binding surface of
human tTFIIB[C] (Right). Areas colored in blue, white, and red
denote positive, neutral, and negative potential contoured at
+3, 0, −3 kT/e, respectively. Black arrows in panels A and C
indicate the basic patches in tTFIIB[C] and the corresponding
regions (recognition loop and HTH motif) in human TFIIB[C]. (B)
In the human TFIIB[C]/TBP/DNA complex, TFIIB[C] contacts the DNA
at BRE^D and BRE^U through its basic surface (29). TBP, which
binds the minor groove, is omitted for clarity. (C) Ribbon
diagram of putative DNA binding surface. The green arrow
indicates the additional turn on H2 unique to the trypanosome
protein. View in this figure is rotated 180° around the
horizontal axis relative to Fig. 2.
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