Figure 4.

Alp14 tip tracks at plus ends of S. pombe MTs and accelerates their growth (A) Schematic of experiment. MTs were grown by polymerising unlabeled single isoform S. pombe tubulin on to stabilised fluorescently labelled seeds that were tethered to the coverslip using anti-fluorophore antibodies. Dynamics were visualized using darkfield video microscopy. Darkfield illumination was done at a wavelength that did not excite the fluorophore (see Methods). (B) Example darkfield data. The dotted overlay highlights infrequent transitions that occur between phases of linear growth. The green band in the kymographs is the fluorescent MT seed. (C) Mean plus end growth rate of S. pombe MTs increases linearly with increasing Alp14 concentration. (D) Minus end growth rate is unaffected. (E) Alp14-GFP tip tracks on unlabeled S. pombe MTs (Inset) MT growth rate increases with increasing Alp14-GFP occupancy of MT tips.