Figure 24-37b



Figure 24-37a

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X-ray structure of the yeast GAL4 DNA-binding domain in complex with a palindromic 19-bp DNA (except for the central base pair) containing the protein's consensus binding sequence. (top) The complex of the dimeric protein with the DNA. The DNA is drawn in stick form with C green, N blue, O red, and P orange and with successive P atoms connected by orange rods. The protein is shown in ribbon form with one subunit pink and the other light blue. The two Zn2+ ions bound to each subunit are represented by cyan spheres and their six liganding Cys side chains are drawn in stick form with C green and S yellow. The initial view is along the complex's 2-fold axis. Click the "Side View" button to view the initial image from its right side so that the 2-fold axis is horizontal. Note how the linkers connecting the N- and C-terminal domains track along the DNA's minor groove and how the C-terminal end of each subunit's N-terminal helix extends into the DNA's major groove where they are separated by 1.5 turns of the DNA helix. (bottom) A ribbon diagram of the protein's zinc finger domain (residues 8–40) colored in rainbow order from its N-terminus (residue 8; blue) to its C-terminus (red). The Cys side chains of its Zn2Cys6 complex are shown in stick form with C green and S yellow, and its Zn2+ ions are represented by cyan spheres. [Based on an X-ray structure by Stephen Harrison and Ronen Marmorstein, Harvard University. PDBid 1D66.]