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The kinetic mechanism of kinesin

2004; Elsevier BV; Volume: 29; Issue: 6 Linguagem: Inglês

10.1016/j.tibs.2004.04.010

1362-4326

Robert A. Cross,

Cellular transport and secretion

The chemical kinetic mechanism of kinesin (K) is considered by using a consensus scheme incorporating biochemically defined open, closed and trapped states. In the absence of microtubules, the dominant species is a trapped K•ADP state, which is defined by its ultra-slow release of ADP (off rate, koff≈0.002 s−1) and weak microtubule binding (dissociation constant, Kd≈10–20 μM). Once bound, this trapped state equilibrates with a strongly binding open state that rapidly releases ADP (koff≈300 s−1). After ADP release, Mg•ATP binds (on rate, kon≈2 μM−1 s−1) driving formation of a closed state that is defined by hydrolysis competence and by strong binding to microtubules. Hydrolysis (khyd≈100–300 s−1) and phosphate release (koff>100 s−1) both occur in this microtubule-bound closed state. Phosphate release acts as a gate that controls reversion to the trapped K•ADP state, which detaches from the microtubule, completing the cycle.