Stochastic kinetics of a single-headed motor protein: dwell time distribution of KIF1A

Abstract

KIF1A, a processive single-headed kinesin superfamily motor, hydrolyzes adenosine triphosphate (ATP) to move along a filamentous track called microtubule. The stochastic movement of KIF1A on the track is characterized by an alternating sequence of pause and translocation. The sum of the durations of pause and the following translocation defines the dwell time. Using the NOSC model (Nishinari K. et al., Phys. Rev. Lett., 95 (2005) 118101) of individual KIF1A, we systematically derive an analytical expression for the dwell time distribution. More detailed information is contained in the probability densities of the "conditional dwell times" τ_±± in between two consecutive steps each of which could be forward (+) or backward (-). We calculate the probability densities ≡_±± of these four conditional dwell times. However, for the convenience of comparison with experimental data, we also present the two distributions ≡_± of the times of dwell before a forward (+) and a backward (-) step. In principle, our theoretical prediction can be tested by carrying out single-molecule experiments with adequate spatio-temporal resolution.