X-ray structure of a monomer of the human p53 DNA binding domain in complex with DNA containing its target sequence. The DNA is drawn in stick form colored according to atom type (C green, N blue, O red, and P orange) with successive P atoms in the same chain joined by orange rods. The protein is shown in ribbon form colored in rainbow order from its N-terminus (blue) to its C-terminus (red). A tetrahedrally liganded Zn²⁺ ion is represented by a magenta sphere, and the side chains of the six most frequently mutated residues in human tumors are shown in stick form with C yellow. Click the "Mutation Sites" buttons to show or hide these side chains. [Based on an X-ray structure by Nikola Pavletich, Memorial Sloan-Kettering Cancer Center, New York, New York. PDBid 1TSR.]