Conserved and divergent features of PF curvatures. (A) Average shapes of KMT ram’s horn PFs from PtK1 and budding yeast compared with analogous PFs from MTs depolymerizing in vitro (D). (B) Mean local curvatures as a function of distance from the MT wall for all ram’s horn PFs from the KMTs of each species studied versus those from polymerizing (P-MTs) and depolymerizing MTs (D-MTs) in vitro. Colors are as in Fig. 4 B, both here and in C and G. (C) Analogous graph of the “intermediate” PFs from all species. (D) Comparison of mean local curvatures for intermediate PFs from nematode KMTs in metaphase and anaphase versus from non-KMTs. (E) Histograms of mean curvatures of intermediate PFs from KMTs 16–23 nm from the MT wall. (F) Local PF curvatures for three classes of MTs from S. pombe. Curvatures of KMTs and non-KMT PFs are similar, but ipMTs are different, both visually and in a test for significance (asterisks) using the unpaired Student’s t test with 95% confidence intervals. (G) Average local curvatures of all PF classes for non-KMTs compared with C. (H) Lengths of PFs versus fibrils in all species studied. For each new species, 100 fibrils were measured on each of two metaphase cells; the numbers of PFs studied are as in Table 1. Error bars indicate SEMs.
