Fig. 2.

Sketch of the main features of the system. (A) Confocal side-view image of a membrane tube representing the typical geometry of the system and suggesting the natural regions dividing it. The binding sites of motors were not specifically labeled. (Bar, 2 μm.) (B) Schematic representation of the different regions (vesicle, tube, and tip). (C) Sketch of the tube-tip boundary and tip region representing the accumulation process at the tip (V < V₀). V is the velocity of the tube and of bound motors at the tip; V₀ is the zero-load velocity of bound kinesins. k⁰_u and k_b are the unbinding rate at zero load and the binding rate of kinesins onto MTs, respectively. We schematically represent the accumulation of motors at the tip. (D) Binding a biotinylated kinesin to a rhodamin-labeled biotinylated lipid (DHPE-Biot-Rhod) through a streptavidin molecule.