The function of ENSG00000054523 (KIF1B, kinesin family member 1B) is as follows. Has a plus-end-directed microtubule motor activity and functions as a motor for transport of vesicles and organelles along microtubules. . [Isoform 2]: Has a plus-end-directed microtubule motor activity and functions as a motor for anterograde synaptic vesicle transport along axonal microtubules from the cell body to the presynapse in neuronal cells (By similarity). Functions as a downstream effector in a developmental apoptotic pathway that is activated when nerve growth factor (NGF) becomes limiting for neuronal progenitor cells (PubMed:18334619). {ECO:0000250|UniProtKB:Q60575, ECO:0000269|PubMed:18334619}. [Isoform 3]: Has a plus-end-directed microtubule motor activity and functions as a motor for anterograde transport of mitochondria. .