FIGURE 2.

MutSαΔ12 and MutSαΔ341 are proficient in mismatch binding, but defective in PCNA interaction. A, the schematic depicts the domain organization of MSH6, MSH6Δ12, and MSH6Δ341, all of which contain domains I-V (14). The N-terminal PCNA-binding motif (gray box) is lacking in MSH6Δ12 and MSH6Δ341. The N-terminal amino acid sequences are shown for full-length MSH6 and MSH6Δ12. Recombinant full-length MSH6 used in this study contained a Gly at position 2 that was introduced during cloning of the gene (S. Gradia and R. Fishel, personal communication). B, MutSαΔ12 (9 μm in column load) was subjected to equilibrium gel filtration on a column equilibrated with 1 μm (solid line) or 4 μm (dotted line) PCNA as described in the legend to Fig. 1. C, shown are the results from SDS-PAGE analysis of PCNA binding to MutSα variants bound to magnetic bead-linked 41-bp G-T heteroduplex or A·T homoduplex DNA (see “Experimental Procedures”).