Structural model of MutSα in complex with a 15 base pair duplex DNA containing a central G-T mismatch. DNA is shown in light blue with the mismatch pair marked: black for guanine and ochre for thymine. The color code for the heterodimer domains is: red for the mismatch binding domain, residues 1 to 124 in MSH2 and 1 to 157 in MSH6; yellow for the connector domain, residues 125 to 297 in MSH2 and 158 to 356 in MSH6; green for the lever domain, residues 300 to 456 and 554 to 619 in MSH2, and 357 to 573 and 648 to 714 in MSH6; purple for the clamp domain, residues 457 to 553 in MSH2 and 574 to 647 in MSH6; blue for the ATP-ase domain, residues 620 to 855 in MSH2 and 715 to 974 in MSH6. Note that in our system, residue 1 of MSH6 corresponds to residue 362 in the solved structure.