Mammalian myosin IXb (Myo9b) has been shown to exhibit unique motor properties in that it
is a single-headed processive motor and the rate-limiting step in its chemical cycle is ATP
hydrolysis. Furthermore, it has been reported to move toward the minus-and the plus-end of
actin filaments. To analyze the contribution of the light chain-binding domain to the
movement, processivity, and directionality of a single-headed processive myosin, we
expressed constructs of Caenorhabditis elegans myosin IX (Myo9) containing either the …