Kinesin-1 takes JIP1 (green) to axon tips, but not if FEZ1 (red) activity is blocked (bottom).

It takes two to turn on a kinesin, say Blasius et al. on page 11. Kinesin-1 motoring on microtubules requires cargo plus a second binding partner to relieve the motor of its inhibited conformation.

On its own, Kinesin-1 is an inactive motor. Inhibition of the solitary motor probably ensures that it is not needlessly burning ATP or clogging up the microtubule roadways when cargo-loaded motors need to get through.

Truncated versions of Kinesin-1 are more active than the full-length protein, suggesting that the deleted domains are autoinhibitory. Cargo binding is thought to activate Kinesin-1 by releasing inhibitory domains from the motor. One recently identified cargo is a scaffolding protein called JIP1, but the group now finds that binding of this cargo is not enough to activate Kinesin-1.

JIP1...

The Rockefeller University Press
2007
The Rockefeller University Press
2007
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