Monitoring Editor: Suzanne Pfeffer Kinesin-1 is a heterotetramer composed of kinesin heavy chain (KHC) and kinesin light chain (KLC). The C. elegans genome has a single KHC, encoded by the
unc-116 gene, and two KLCs, encoded by the
klc-1 and
klc-2 genes. We show here that UNC-116/KHC and KLC-2 form a complex orthologous to conventional kinesin-1. KLC-2 also binds UNC-16, the C. elegans JIP3/JSAP1 JNK-signaling scaffold protein, and the UNC-14 RUN domain protein. The localization of UNC-16 and UNC-14 depends on kinesin-1 (UNC-116 and KLC-2). Furthermore, mutations in
unc-16,
klc-2,
unc-116, and
unc-14 all alter the localization of cargos containing synaptic vesicle markers. Double mutant analysis is consistent with these four genes functioning in the same pathway. Our data support a model whereby UNC-16 and UNC-14 function together as kinesin-1 cargos and regulators for the transport or localization of synaptic vesicle components.