The use of native thick filaments in in vitro motility assays

Native thick filaments from the clam, Mercinaria mercinaria translocate actin filaments both toward and away from the center of the thick filament in an in vitro motility assay. The thick filaments from the adductor muscle are about 10 microns long whereas those from the catch muscle are 30-50 microns long. These thick filaments should prove useful in understanding the mechanism of myosin-dependent movement of actin filaments.