Members of the UNC-104/KIF-1 family play important role in neural growth, axonal transport and synaptic function. In C. elegans in addition to UNC-104, two similar motors KLP-4 and KLP-6 comprise the Kinesin-3 family subgroup (Siddiqui 2002) characterized by an amino-terminal Motor head domain (ATP and microtubule binding sites), followed by a coiled coil stalk hinge region for multimer formation and a carboxyl terminal tail domain of variable length and composition and is similar to the GAKIN 13A family of mammalian motors (Hanada et al., 2002). We have shown that inhibition of
klp-4 function by RNAi an
rrf-3 mutant background results in embryonic arrest and reduction in brood size. A
klp-4::gfp promoter fusion transgene expresses in the sensory neurons in the head, a set of ventral cord motor neurons, and the sensory ray neurons in the male tail ray neurons and the intestine from larval stages L1-L4 and in adults. Polyclonal antibodies raised against the carboxyl terminal of the KLP-4 detect a 180-kDa band. Immunostaining with an affinity purified anti-KLP-4 antibody shows that the KLP-4 motor is present in the sensory neurons in the head, developing embryos, germ cells and intestine, consistent with the
klp-4::gfp expression results. The KLP-4 also contains the fork-head association domain (residues 534-594) suggesting a motif for protein-protein interaction. We are examining the stalk and tail region of the KLP-4 motor using
klp-4::gfp constructs to determine the cell specificity of
klp-4 expression. Expression of
klp-4 closely resembles that of
klp-6 another member of the UNC-104 family of kinesins enriched in sensory neurons and motor neurons. A mutation in
klp-6 aka
lov-2(
sy511) has been described (Paden and Barr, 2004). Expression of
klp-4::gfp in
lov-2 background may reveal epistasis. Similar interactions between
klp-6 and
unc-104 are under investigation.