Figure 6. Model of kinesin-5 function in Drosophila neurons.

Kinesin-5/Klp61F undergoes several critical steps to function properly in neurons: (1) Kinesin-5/Klp61F must leave the soma, a process that requires its motor domain, as motorless Klp61F remains exclusively localized in the neuronal cell body; (2) Kinesin-5/Klp61F must enter the axon, a process dependent on its stalk domain, since the human Eg5 motor lacking the Klp61F stalk domain is mislocalized entirely to the dendrites; (3) The full-length, active tetramer of kinesin-5/Klp61F acts as a dynamic brake on microtubule sliding driven by kinesin-1 at the axon growth cone, playing an essential role in axon pathfinding by responding to both attractive and repulsive cues.