• alternative splicing;
  • KIF1B protein;
  • kinesin;
  • lysosomes;
  • microtubules

The kinesin superfamily protein, KIF1Bβ, a splice variant of KIF1B, is involved in the transport of synaptic vesicles in neuronal cells, and is also expressed in various non-neuronal tissues. To elucidate the functions of KIF1Bβ in non-neuronal cells, we analyzed the intracellular localization of KIF1Bβ and characterized its isoform expression profile. In COS-7 cells, KIF1B colocalized with lysosomal markers and expression of a mutant form of KIF1Bβ, lacking the motor domain, impaired the intracellular distribution of lysosomes. A novel isoform of the kinesin-like protein, KIF1Bβ3, was identified in rat and simian kidney. It lacks the 5th exon of the KIF1Bβ-specific tail region. Overexpression of KIF1Bβ3 induced the translocation of lysosomes to the cell periphery. However, overexpression of KIF1Bβ3-Q98L, which harbors a pathogenic mutation associated with a familial neuropathy, Charcot-Marie-Tooth disease type 2 A, resulted in the abnormal perinuclear clustering of lysosomes. These results indicate that KIF1Bβ3 is involved in the translocation of lysosomes from perinuclear regions to the cell periphery.