Fig. 5. Auto-inhibition of kinesin I motor activity by folding. In the absence of cargo, kinesin I is in a folded conformation wherein the C-terminus of KHC interacts with the motor domain to prevent binding to the microtubule. How kinesin I is activated is unknown. One hypothesis is that cargo binding (to either the KLC or the KHC cargo binding sites) induces a conformational change that frees the motor domain to engage the microtubule.