A model system to study transport of self-assembled cargos

Intracellular transport is the process by which cellular cargos, such as organelles and proteins, are moved throughout the cell. Motor proteins bind these cargos and walk along microtubule tracks to deliver them to specific regions of the cell. In axons, cargos are transported by either fast or slow axonal transport. Fast axonal transport is performed by fixed teams of motors bound to membranous cargos, whereas slow axonal transport is thought to be performed by motors that transiently self-assemble with cargos, assembling and disassembling throughout transport. While recent studies have begun to shed light on the nature of slow axonal transport, there are many open questions about the mechanism of action for transient motor association, and how they could result in effective, yet slow, long-range transport. Here, we describe an in vitro system to study self-assembled cargos using quantum dots (Qdots) as artificial cargos. In this system, kinesin motors are able to form transient interactions with Qdot cargos, allowing for the study of self-assembled cargos that assemble and disassemble during transport. Using this system, we can begin to probe the effects of self-assembly on cargo transport properties.