Slow axonal transport : the polymer transport model

About 20 years ago, Lasek and colleagues proposed that cytoskeletal proteins are transported along axons as assembled polymers, and cytosolic proteins are transported coordinately by association with these polymers. Over the years, this hypothesis has met with repeated challenges from workers who favour a model in which cytoskeletal proteins are actively transported along axons as free subunits or small oligomers that assemble into stationary cytoskeletal polymers. Here, we discuss the major evidence relevant to this controversy and explain why we believe that polymer transport remains the most plausible model for slow axonal transport.