CEP97^CP110 forms caps at the plus ends of dynamic MT and straightens their PFs. (A) Slices through denoised tomograms containing MT plus ends in the absence or presence of 80 nM CEP97^CP110-GFP and 15 µM tubulin. (B) Segmented and 3D rendered volumes containing MT plus ends (blue), capping density (green), and manually segmented 3D models of traced PF shapes (orange). Arrows point to soluble tubulin oligomers. (C) Fraction of MT ends associated with a capping density. Data points show individual grids, line shows mean ± SD. (D) Scheme showing the parameters extracted from manual segmentations of terminal PFs. (E) All PF traces obtained from plus ends, aligned at their origin, in presence of 15 µM tubulin alone (right), with CEP97^CP110-GFP cap (middle) and uncapped in presence of CEP97^CP110 (right). (F–H) Average PF lengths (F), average curvatures (G), and average terminal curvatures (H) of PFs with nonzero length for samples imaged in the presence of 15 µM soluble tubulin. Shown are average values within each MT (dots), their mean and SD (error bars); ****P < 0.0001, *P < 0.05; ns—nonsignificant with one-way ANOVA followed by Tukey’s multiple comparison test; n is the number of MTs analyzed for each data set. Data distribution was assumed to be normal, but this was not formally tested. (I) Mean ± SEM of the curvature of PFs, aligned at their distal tips. The straight lines show the results of linear fitting. (J) Correlation between average curvature and average PF length per MT plus end. r, Pearson correlation coefficient; p, probability that the slope of the correlation is different from zero; and n showing number of MTs is mentioned in the figure.