CPC coacervates generate bundles of MTs.A, CPC condensates concentrate free tubulin. DIC and fluorescence images of rhodamine-labeled tubulin dimers partitioning into CPC coacervates (n = 43). Experiment was repeated multiple times during the course of the project using different CPC preps (n = 3 preps). Box and whisker graph represents the median (central line), 25th to 75th percentile (bounds of the box), and 5th to 95th percentile (whiskers). B, CPC condensates generate tapered MT bundles in the presence of GTP. GFP-CPC was incubated with rhodamine-labeled tubulin and GTP as indicated. Experiment was repeated twice. C, bundles of MTs generated in the presence of phase-separated CPC imaged by TIRF microscopy after the indicated time. Experiment was repeated multiple times during the course of the project using three different CPC preps; scale bar for A, B, and C represents 5 μm. D, cryo-EM images of bundles of MTs generated by the CPC. E, 3D reconstruction of single MTs generated by the CPC. Cryo-EM measurements were done twice from two independent CPC preps. CPC, chromosomal passenger complex; DIC, differential interference contrast; MT, microtubule; TIRF, total internal reflection fluorescence.