Self-Organization of Minimal Anaphase Midzone Bundles
(A) Schematic of PRC1 (top) and KIF4A (bottom) domains and interactions.
(B) Schematic of the formation of minimal anaphase midzone bundles.
(C) Triple-color TIRF microscopy images showing the time course of self-organization of antiparallel microtubule bundles in the presence of 20-nM PRC1-Alexa546 (green), 50-nM KIF4A-mBFP (blue), and 12.5-μM Alexa647-tubulin (red). Times in minutes after initiating microtubule nucleation by a temperature shift to 30°C are shown. See Video S1.
(D) Single- and triple-color TIRF microscopy image sequences (top) and kymographs (bottom) showing PRC1 and KIF4A accumulation in the central part of the antiparallel microtubule bundle; condition as in (C).
(E) TIRF microscopy image of individual microtubules polymerized in a solution containing 50-nM KIF4A-mBFP (blue) and 12.5-μM Alexa647-tubulin (red), taken 20 min after initiating nucleation.
(F) TIRF microscopy image of microtubule bundles polymerized in the presence of 20-nM PRC1-Alexa546 (green) and 12.5-μM Alexa647-tubulin (red), taken 20 min after initiating nucleation. See Video S2.
(G and H) Average normalized PRC1 fluorescence intensity profiles along the bundle axis at 30 min, for microtubule bundles formed in the presence of 20-nM PRC1 only (G; n = 9) and with 20-nM PRC1 and 50-nM KIF4A (H; n = 14). The linewidth shows the SE of the average. The profiles have been fit (red line) with a Gaussian (G; σ = 6.6 μm) and Lorentzian distribution (H; σ = 1.5 μm), respectively. The temperature was 30°C.
See also Figures S1 and S6.