Neurospora crassa NKIN2, a kinesin-3 motor, transports early endosomes and is required for polarized growth.

Biological motors are molecular nanomachines, which convert chemical energy into mechanical forces. The combination of mechanoenzymes with structural components, such as the cytoskeleton, enables eukaryotic cells to overcome entropy, generate molecular gradients, and establish polarity. Hyphae of filamentous fungi are among the most polarized cells, and polarity defects are most obvious.