Characean actin bundles as a tool for stydying actomyosin-based motility

At the inner surface of the stagnant chloroplasts of Characeae cells, bundles of actin filaments having uniform polarity are anchored. These bundles are responsible for generating the motive force of cytoplasmic streaming. It is now possible to induce movement of either beads coated with foreign myosin or organelles associated with myosin along the characean actin bundles. The Ca²⁺ sensitivities of the reconstitued movements are consistent with those of the actin-activated myosin ATPases. The use of reconstituted systems is finding wide application in the detection of various myosins in materials from which myosin is not significantly purified. Furthermore, sliding velocities and the Ca²⁺ regulation of myosins bound to organelles are now being determined. Recipient of the Botanical Society Award for Young Scientists, 1987.