Fig. 2: p180 and KTN1 bind glutamylated and polyglutamylated microtubules, respectively.
From: ER proteins decipher the tubulin code to regulate organelle distribution
a, Representative micrographs of p180 and KTN1 fragments (cyan) binding to unmodified microtubules or microtubules glutamylated in vitro by TTLL6 (magenta). Internal reflection microscopy images for the microtubule channel were background subtracted and inverted. Average numbers of glutamate molecules (E) added to microtubules as quantified from mass spectroscopy data in each group are indicated. Scale bar, 5 μm. b, Binding of p180 and KTN1 fragments to unmodified and TTLL6-glutamylated microtubules. n = 110 (unmodified), 165 (α + 3.5 E, β + 1.3 E) and 112 (α + 8.3 E, β + 2.6 E) microtubules for p180; n = 141 (unmodified), 186 (α + 3.5 E, β + 1.3 E) and 156 (α + 8.3 E, β + 2.6 E) microtubules for KTN1. c, Representative micrographs of p180 and KTN1 microtubule interacting fragments (cyan) showing binding to unmodified microtubules or microtubules glutamylated by TTLL4 or TTLL7 (magenta). KTN1 and p180 are shown with different brightness/contrast settings for TTLL4- and TTLL7-modified microtubules, reflecting large differences in binding between mono- and polyglutamylated microtubules. Scale bar, 5 μm. d, e, Affinities of p180 and KTN1 for unmodified microtubules and microtubules glutamylated by TTLL7 (d) or TTLL 4 (e). The x-axis shows weighted averages of glutamate residues attached to α- and β-tubulin. n = 185 (unmodified) and 117 (α + 0 E, β + 1.2 E) microtubules for p180; n = 128 (unmodified) and 225 (α + 0 E, β + 1.2 E) microtubules for KTN1; n = 179 (unmodified) and 237 (α + 0 E, β + 1.5 E) microtubules for p180; n = 163 (unmodified) and 224 (α + 0 E, β + 1.5 E) microtubules for KTN1. f, CLIMP63 binds centrosomal microtubules, KTN1 binds perinuclear polyglutamylated microtubules, and p180 can bind peripheral microtubules with less glutamylation. Together, these proteins maintain proper asymmetric ER distribution, which regulates organelle distributions. MT, microtubules. Data are mean ± s.d. with individual data points shown. Kruskal–Wallis (b) or Mann–Whitney tests (d, e); P values are shown.
