Kinesin carries the signal

Conventional kinesin has long been known to be a molecular motor that trans ports vesicular cargo, but only recently have we begun to understand how it functions in cells. Regulation of kinesin involves self-inhibition in whic h a head-to-tail interaction prevents microtubule binding. Although the mec hanism of motor activation remains to be clarified, recent progress with re spect to cargo binding might provide a clue. Kinesin binds directly to the JIPs (JNK-interacting proteins), identified previously as scaffolding prote ins in the JNK (c-Jun NH2-terminal kinase) signaling pathway. The JIPs can allow kinesin to transport many different cargoes and to concentrate and re spond to signaling pathways at certain sites within the cell. The use of sc affolding proteins could be a general mechanism by which molecular motors l ink to their cargoes.