Two heteromeric kinesin complexes in chemosensory neurons and sensory cilia of Caenorhabditis elegans

Chemosensation in the nervous system of the nematode Caenorhabditis elegans depends on sensory cilia, whose assembly and maintenance requires the tran sport of components such as axonemal proteins and signal transduction machi nery to their site of incorporation into ciliary structures. Members of the heteromeric kinesin family of microtubule motors are prime candidates for playing key roles in these transport events. Here we describe the molecular characterization and partial purification of two heteromeric kinesin compl exes from C. elegans, heterotrimeric CeKinesin-II and dimeric CeOsm-3. Tran sgenic worms expressing green fluorescent protein driven by endogenous hete romeric kinesin promoters reveal that both CeKinesin-II and CeOsm-3 are exp ressed in amphid, inner labial, and phasmid chemosensory neurons. Additiona lly, immunolocalization experiments on fixed worms show an intense concentr ation of CeKinesin-II and CeOsm-S polypeptides in the ciliated endings of t hese chemosensory neurons and a punctate localization pattern in the corres ponding cell bodies and dendrites. These results, together with the phenoty pes of known mutants in the pathway of sensory ciliary assembly, suggest th at CeKinesin-II and CeOsm-3 drive the transport of ciliary components requi red for sequential steps in the assembly of chemosensory cilia.