The kinetic mechanism of kinesin.
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, k(off) approximately 0.002 s(-1)) and weak microtubule binding (dissociation constant, K(d) approximately 10-20 microM). Once bound, this trapped state equilibrates with a strongly binding open state that rapidly releases ADP (k(off) approximately 300 s(-1)). After ADP release, Mg*ATP binds (on rate, k(on) approximately 2 microM(-1)s(-1)) driving formation of a closed state that is defined by hydrolysis competence and by strong binding to microtubules. Hydrolysis (k(hyd) approximately 100-300 s(-1)) and phosphate release (k(off)>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.
Cross
Robert A
RA
Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 0TL, UK. r.cross@mcri.ac.uk
D000244:Adenosine Diphosphate / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D006801:Humans; D006868:Hydrolysis; D016547:Kinesins / Q000737:chemistry*; D007700:Kinetics; D008870:Microtubules / Q000737:chemistry; D008958:Models, Molecular; D010710:Phosphates / Q000737:chemistry
D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D016547:Kinesins