(a) Figure 24-36


(b) Central zinc finger

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X-ray structure of the three-zinc finger segment of Zif268 in complex with a 10-bp DNA. (a) The complex of the entire protein segment with a 10-bp DNA with a single nucleotide overhang at each end. The DNA is drawn in stick form with C magenta, N blue, O red, and P orange and with successive P atoms connected by orange rods. The protein is drawn in cartoon form with finger 1 light blue, finger 2 colored in rainbow order from its N-terminus (blue) to its C-terminus (red), and finger 3 yellow. The Zn2+ ions are represented by cyan spheres and their liganding His and Cys side chains are drawn in stick form with C green, N blue, and S yellow. (b) A ribbon diagram of the central zinc finger motif (finger 2) represented as that in Part a. Click on the "Show DNA Binding Region" button to see how the N-terminal end of Finger 2's helix fits into the DNA major groove to contact three base pairs. [Based on an X-ray structure by Carl Pabo, MIT. PDBid 1ZAA.]