TABLE 3.
Analytical model predicting the probability of switching protofilaments at various RK concentrations and comparison to experimental data
| P0 (step) | P0 (sidestep) | P0 (det) | PRB (sidestep) | RK Level | P (obstacle) | Ptot (sidestep) | Expected PF Switches/μm | Measured PF Switches/μm | |
|---|---|---|---|---|---|---|---|---|---|
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| Kinesin-1 | 0.990 | 0.0047 | 0.0053 | 0.47 | No RK | 0.000 | 0.0047 | 0.57 | 0.57 |
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| Low RK | 0.002 | 0.0056 | 0.69 | 0.57 | |||||
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| High RK | 0.006 | 0.0075 | 0.92 | 0.41 | |||||
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| Kinesin-2 | 0.947 | 0.0180 | 0.0079 | 0.69 | No RK | 0.000 | 0.0180 | 2.20 | 2.20 |
|
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| Low RK | 0.002 | 0.0194 | 2.36 | 2.19 | |||||
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| High RK | 0.006 | 0.0221 | 2.70 | 2.48 | |||||
Analytical model describing kinesin protofilament (PF) switch frequency by incorporating both intrinsic and induced sidesteps when encountering an obstacle or roadblock. The model replicates the kinesin-2 frequency data, but not the kinesin-1, indicating kinesin-2 switches protofilaments during an encounter. See results section above for analytical expression. P0(step) is the probability of taking a forward step in the absence of obstacles, P0(sidestep) is the experimentally observed intrinsic sidestepping frequency, P0(det) is the detachment rate per step, PRB(sidestep) is the probability of an induced sidestep during an obstacle encounter, P(obstacle) is the simulated obstacle density, and Ptot(sidestep) is the total probability of switching protofilaments. Expected PF Switches / μm is calculated by dividing the total probability of switching PFs by the tubulin dimer spacing of 0.0082 μm.