Controlling the direction of kinesin-driven microtubule movements along microlithographic tracks

Motor proteins are able to move protein filaments in vitro. However, useful work cannot be extracted from the existing in vitro systems because filame nt motions are in random directions on two-dimensional surfaces. We succeed ed in restricting kinesin-driven movements of microtubules along linear tra cks by using micrometer-scaled grooves lithographically fabricated on glass surfaces. We also accomplished the extraction of unidirectional movement f rom the bidirectional movements along the linear tracks by adding arrowhead patterns on the tracks. These "rectifiers" enabled us to construct micromi niturized circulators in which populations of microtubules rotated in one d irection, and to actively transport microtubules between two pools connecte d by arrowheaded tracks in the fields of micrometer scales.