The UNC-104/KIF1 family of kinesins.

Most UNC-104/KIF1 kinesins are monomeric motors that transport membrane-bounded organelles toward the plus ends of microtubules. Recent evidence implies that KIF1A, a synaptic vesicle motor, moves processively. This surprising behavior for a monomeric motor depends upon a lysine-rich loop in KIF1A that binds to the negatively charged carboxyl terminus of tubulin and, in the context of motor processivity, compensates for the lack of a second motor domain on the KIF1A holoenzyme.