. 2014 Oct 21;107(8):1896–1904. doi: 10.1016/j.bpj.2014.09.009

Table 1.

The force-dependent off-rates, k_off(F), for different motors in the hindering and assistive directions

Kinesin	k^hind_off (F) [s⁻¹]	k^asst_off (F) [s⁻¹]
1	0.79e^−F/6.1	0.79 + 1.56F
2	8.37e^−0.07F – 7.49e^0.43F	15.0e^F/2.0
3	1.433e^\|F\|/0.5
5	0.046e^\|F\|/1.5
7	0.328e^\|F\|/2.6

Values for kinesin-1 were taken from experimental data (28). Note that the value of F_c under hindering loads is higher than the value of 3 pN frequently used in simulations because the latter value refers to run-length data (34). Inasmuch as k_off = velocity/run length, taking into account the load dependence of velocity results in the larger F_c used here. For kinesin-2, k_off(F) in the hindering direction was measured experimentally (28), but under assisting loads motors readily dissociated, precluding a reliable estimate. The limit of detection for measuring speeds was ∼5 steps, giving a lower limit of 10 s⁻¹, and iterative fits to experimental speed data resulted in an estimate of k_off(0) = 15 s⁻¹ with an exponential dependence. All parameters obtained from modeling are shown in boldface, and forces are in picoNewtons.