Fig 5. MutSα binds to both strands of the FX repeat and promotes binding of MutSβ.

MutSα and/or MutSβ with the N-terminal truncation of MSH3 were added at the indicated concentrations to reaction mixtures containing the CCG repeat and CGG repeat-containing substrates as described in the Materials and Methods. The DNA and DNA:protein complexes were then resolved by native polyacrylamide gel electrophoresis at 4˚C, transferred to nylon membrane and the DNA detected using streptavidin conjugated to horseradish peroxidase (HRP) and a chemiluminescent substrate. The different DNA:MutS complexes are numbered in order of decreasing mobility. The arrowheads indicate novel shifted bands that are not seen in reactions containing either MutSα or MutSβ alone.