Figure 2: Measurement of viscous drag of membrane-bound Myo1c.
Ensemble averages of normalized force relaxation traces obtained from oscillating actin filaments (a) away from the pedestal surface and (b) touching the top of the pedestal in the absence of Myo1c, and adjacent to the pedestal in the presence of (c) 0.2 pM, (d) 0.6 pM, and (e) 1.9 pM of Myo1c. The black and blue traces are averages of normalized force relaxation traces in the presence and the absence of actoMyo1c-membrane attachment respectively according to the parsing criterion (see text). Dashed red lines are error-weighted fits of the corresponding average traces to a single exponential decay function. Error bars are standard deviations of the mean. (Insets, blue bars, left axis) Frequency distribution of S5 values for all relaxation traces from a single experiment over multiple oscillation cycles (for the total percentage of the different types of relaxation over the whole datasets under each condition see Table 1). (Black bars, right axis) Distribution of S5 values identified as exponentially decaying force relaxation events during an actoMyo1c-membrane attachment. Blue bars to the left of black bars correspond to relaxation events in the absence of actoMyo1c-membrane attachment. Dashed red lines are fits of the predominant peaks (blue bars to the left of the black bars) to a Gaussian function. (f) Distribution of the diffusion coefficients (DMyo1c) obtained for membrane-bound Myo1c from fitting the individual force relaxation traces for actoMyo1c-membrane attachments identified in the presence of 0.2 pM and 0.6 pM Myo1c (see text for details). (Inset) The same data plotted as a cumulative distribution.
