Direct observation of processive movement by individual myosin V molecules |
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Authors: | Sakamoto T Amitani I Yokota E Ando T |
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Institution: | Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa-ken, 920-1192, Japan. |
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Abstract: | Myosin V is an unconventional myosin thought to move processively along actin filaments. To have hard evidence for the high processivity, we sought to observe directly the movement by individual native chick brain myosin V (BMV) molecules with fluorescent calmodulin. Single BMV molecules did exhibit highly processive movement along actin filaments fixed to a coverslip. BMV continued to move up to the barbed end of its actin track, and did not readily detach from action. The barbed end, therefore, got brighter with time, because of a constant stream of BMV traffic. The maximum speed of the processive movement was 1 microm/s, and the maximum actin-activated ATPase rate was 2.4 s(-1). These values apparently imply that BMV travels a great distance, 400 nm, per an ATPase cycle. |
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