Myosin-V stepping kinetics: a molecular model for processivity.

Rief, M; Rock, R S; Mehta, A D; Mooseker, M S; Cheney, R E; Spudich, J A · Proc Natl Acad Sci U S A · 2000

basic_science · Level V

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Abstract

Myosin-V is a molecular motor that moves processively along its actin track. We have used a feedback-enhanced optical trap to examine the stepping kinetics of this movement. By analyzing the distribution of time periods separating discrete approximately 36-nm mechanical steps, we characterize the number and duration of rate-limiting biochemical transitions preceding each such step. These data show that myosin-V is a tightly coupled motor whose cycle time is limited by ADP release. On the basis of these results, we propose a model for myosin-V processivity.

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