Fig. 2.

Evolution of tubular networks. (a) A typical example of the evolution of the total length of membrane tubes pulled from vesicles for different final concentrations of kinesin in the sample: 10 μg/ml (filled circles), 3 μg/ml (open squares), 1 μg/ml (open circles), and 0.1 μg/ml (filled squares). In each sample, ≈15 vesicles were present in the field of view. Time 0 corresponds to the end of sample preparation. No tubes are formed at the lower concentrations, whereas, for the higher concentrations, tubes start to form after sedimentation. (b) Typical example of the total tube length pulled from vesicles with the pore-forming drug SLO and cholesterol (filled circles), normal vesicles (filled squares), and vesicles with only cholesterol (open circles). In the presence of SLO the forces needed to pull tubes are much lower than for normal vesicles, whereas with only cholesterol present they are higher (see Fig. 3). The kinesin concentration is 2 μg/ml.