Acetylated MTs and ER sliding events correlate with MT curvature. (A) Immunofluorescence staining of α-tubulin and acetylated α-tubulin on untreated cells. (B) Diagram of curvature. (C, left) Graph of curvature of acetylated (n = 37) or nonacetylated MTs (n = 37). Acetylated MTs were picked by drawing a line through the cell at a point containing the maximum number of acetylated MTs. α-Tubulin staining of MTs that were not acetylated were picked along that line if they were isolated at the line. The mean curvature of the MT for 2.5 µm on either side of the line (or 5 µm total) was determined by “imodcurvature.” (right) The frequency of MT curvature in groups of indicated values for nonacetylated MTs or acetylated MTs. (D) Curvature measurements for dynamic MTs (labeled with EB3; n = 37), TAC MTs (labeled with YFP-STIM1; n = 16), and ER sliding MTs (GFP–Sec61-β; n = 41). Right panel shows frequency of each event. (C and D) Error bars show standard deviation. P-values were determined by unpaired t test: **, P = 3.7 × 10−7 (C); and **, P < 0.001 (D). Bar, 10 µm.
