Impact of the number of motors on cargo on the switching probability and pause duration at microtubule intersections.

Cells achieve proper distribution of cargo like vesicles and organelles using molecular motor-based transport on cytoskeletal networks. Rapid redistribution of cargoes, like during color change in melanophores, is believed to be achieved by varying parameters like the switching probability at cytoskeletal intersections. The switching probability depends on various parameters like the cargo size, whether the cargo is moving on an overpass or underpass, etc. It is unclear how other relevant parameters like the number of motors on cargo, and network properties like the intersection angle impact switching and pausing. To explore these features, we collected fluorescence microscope videos of Qdot on in-vitro networks of MTs for different numbers of motors on cargo. We then tracked cargo trajectories and analyzed pause duration, switching probability, velocity distribution, etc. To get a better estimate of switching probability, we extracted MT network data from the experimental images, ran coarse-grained simulations on the network, and compared experimental and simulated trajectories. Our work provides new insights into the importance of motor concentration, and network properties on intracellular transport. We also share a unique method of measuring switching probability from experimental trajectories.