FIGURE 6.

Autoinhibition is stabilized by Ser-175 modification. Analytical ultracentrifugation was used to measure the sedimentation coefficient of full-length wild-type kinesin (blue) and a full-length S175D mutant (red) as a function of the ionic strength of the buffer. Higher sedimentation coefficients were observed for the Ser-175 mutant, indicating an increase in the fraction of autoinhibited S175D relative to wild-type kinesin. The S.E. of the fit produced error bars smaller than the size of the symbols used in the plot.