MIND activates Ndc80 complex binding via the same mechanism as ndc80-121. (A, Top) Diagram of Ndc80 complex denoting Ndc80 microtubule-binding domains (CH domain, N-terminal tail) and position of ndc80-121 mutation (Y465C/I469Q) near the loop domain. Modified from ref. 10 with permission from the Genetics Society of America. (Bottom) Diagram depicting proposed conformational changes of MIND-Ndc80c vs. MIND-Ndc80-121c. (B, Left) Survival probability vs. time quantified from individual binding events for Ndc80c-GFP (N-GFP, n = 355), ndc80-121c-GFP (n-121-GFP, n = 481), MIND-GFP/Ndc80c (M-GFP/N, n = 359), and MIND-GFP/ndc80-121 (M-GFP/n-121, n = 426) at the restrictive temperature (37 °C). (Right) Average residence times derived from distributions on Left; error bars denote SD. Ndc80c-GFP is statistically different from Ndc80-121c-GFP, P = 0.003 and MIND-GFP/Ndc80c, P = 0.005 (two-tailed Student’s t test). Ndc80-121c-GFP and MIND-GFP/Ndc80-121c are not statistically different (two-tailed Student’s t test, P = 0.58).