Myosin V walks by lever action and Brownian motion.
Myosin V is a molecular motor that moves cargo along actin filaments. Its two heads, each attached to a long and relatively stiff neck, move alternately forward in a "hand-over-hand" fashion. To observe under a microscope how the necks move, we attached a micrometer-sized rod to one of the necks. The leading neck swings unidirectionally forward, whereas the trailing neck, once lifted, undergoes extensive Brownian rotation in all directions before landing on a site ahead of the leading head. The neck-neck joint is essentially free, and the neck motion supports a mechanism where the active swing of the leading neck biases the random motion of the lifted head to let it eventually land on a forward site.
Shiroguchi
Katsuyuki
K
Department of Physics, Faculty of Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan.
Kinosita
Kazuhiko
K
D000199:Actins / Q000502:physiology; D000818:Animals; D002645:Chickens; D008856:Microscopy, Fluorescence; D009038:Motion; D024701:Myosin Type V / Q000502:physiology*; D011817:Rabbits
D000199:Actins; D024701:Myosin Type V