Fig. 6. Theoretical models and stochastic simulations.
a, Cartoon of a lattice model for motor transport with cargo oligomerization. Reactions include motor movement, attachment, detachment, a growing lattice, the binding and unbinding of cargo to bound motors, and a cargo multi-layer absorption/desorption process. Model parameters are provided in Supplementary Table 2. b, Nucleotide-dependent motor slowdown was implemented by including a GTP cap and two-step hydrolysis. The GTP profile decays exponentially (dashed line, normalized to 0.3) and the amounts of motors and cargos at the lattice end increase. c, Interactions between cargo particles was implemented such that neighbouring cargo particles form a cargo train that induces coherent movement of cargo-motor clusters. Cargo clustering does not lead to increasing amounts of cargo at the lattice end unless a GTP cap is implemented as in b. d, The stability of cargo clusters was increased by dynamically enhancing the motor dwell time in cargo clusters. This mechanism alone did not result in substantial accumulation of cargo, similar to c. However, cargo accumulation increased sharply in combination with a GTP cap. Motor concentration in b–d corresponds to ~100 nM Tea2 in experiments. e, Density profiles of stabilized cargo clusters (blue lines) and independent cargo clusters (orange lines) for a range of motor concentrations between 20 nM and 180 nM. f, The average cargo occupation is shown depending on motor concentration for the microtubule lattice (shaded area in e on the left; dashed lines) and the microtubule tip (shaded area in e on the right corresponding to ~200 nm; solid lines). Numerical data are available in source data.