dam1p S to D mutant specifically showed lower affinity for Ndc80p and Spc34p. (A) Wild type GST-Dam1p pulled down more Ndc80p and Spc34p than GST-dam1p (S to D) mutant. (B) IVT Duo1p and IVT Sli15p showed similar binding to both wild type and mutant Dam1p. (C) IVT Mcm16p did not bind to either wild type or dam1p (S to D) mutant. The binding assays were performed as described in Materials and Methods. IVT Ndc80p, Spc34p, Duo1p and Sli15p all showed saturable and therefore specific binding with both wild type and mutant GST-Dam1p, although the extent of saturation varied by proteins.