DETERMINANTS OF KINESIN MOTOR POLARITY

The kinesin motor protein family members move along microtubules with characteristic polarity. Chimeric motors containing the stalk and neck of the minus-end-directed motor, Ncd, fused to the motor domain of pl us-end-directed kinesin were analyzed. The Ncd stalk and neck reversed kinesin motor polarity, but mutation of the Ncd neck reverted the chi meric motor to plus-end movement. Thus, residues or regions contributi ng to motor polarity must be present in both the Ncd neck and the kine sin motor core. The neck-motor junction was critical for Ncd minus-end movement; attachment of the neck to the stalk may also play a role.