Extreme-value analysis of intracellular cargo transport by motor proteins

Abstract

The mechanisms underlying the chemo-mechanical coupling of motor proteins is usually described by a set of force-velocity relations that reflect the different mechanisms responsible for the walking behavior of such proteins on microtubules. However, the convexity of such relations remains controversial depending on the species, and in vivo experiments are inaccessible due to the complexity of intracellular environments. As alternative tool to investigate such mechanism, Extreme-value analysis (EVA) can offer insight on the deviations in the data from the median of the probability distributions. Here, we rely on EVA to investigate the motility functions of nanoscale motor proteins in neurons of the living worm Caenorhabditis elegans (C. elegans), namely the motion of kinesin and dynein along microtubules. While the essential difference between the two motors cannot be inferred from the mean velocities, such becomes evident in the EVA plots. Our findings extend the possibility and applicability of EVA for analysing motility data of nanoscale proteins in vivo.