Figure 3.

Model for the one-headed kinesin hydrolysis pathway at high ATP concentration and low ADP and P_i concentrations. T, ATP; D, ADP; P, P_i; φ, no nucleotide. For simplicity, nucleotide states not on the principal pathway and reverse rate constants are not shown. Our results argue that detachment occurs in the ADP⋅P_i state. Results from Hackney (41) show that, in the absence of microtubules, reversal of ATP hydrolysis is slow compared with phosphate release and that the rebinding of kinesin⋅ADP to the microtubule is necessary to accelerate ADP release.