The Dynamics of Microtubule Motor-Protein Assemblies in Biology and Physics

Many important processes in the cell are mediated by stiff microtubule polymers and the active motor proteins moving on them. This includes the transport of subcellular structures (nuclei, chromosomes, organelles) and the self-assembly and positioning of the mitotic spindle. Little is understood of these processes, but they present fascinating problems in fluid-structure interactions. Microtubules and motor proteins are also the building blocks of new biosynthetic active suspensions driven by motor-protein activity. These reduced systems can be probed-and modeled-more easily than can the fully biological ones and demonstrate their own aspects of self-assembly and complex dynamics. I review recent work modeling such systems as fluid-structure interaction problems and as multiscale complex fluids.