Figure 3.
Full-length CENP-E is a slow plus end–directed kinetochore motor. (A) Coomassie-stained full-length CENP-E–GFP (366 kD) purified from baculovirus-induced insect cells. (B) Microtubule gliding assay with full-length CENP-E. CENP-E–GFP proteins were tethered to a GFP antibody-coated surface of a flow chamber, and polarity-marked microtubules were subsequently introduced. Minus ends of the microtubules are brightly marked. Colored arrowheads indicate the starting positions of three microtubules, and colored dots indicate the minus ends. The mean gliding velocity was 30 ± 7.6 nm/s (mean ± SD; n = 112). (C) Purified full-length CENP-E–GFP was added into the Xenopus extract before spindle assembly. (D) Added CENP-E–GFP was localized to the kinetochore in Xenopus extract spindle. A frame from a time-lapse video of a metaphase spindle in the Xenopus extracts is shown. Red, X-rhodamine tubulin; green, CENP-E–GFP. Bars: (B) 2 μm; (D) 10 μm.
