Background: Kelch-related proteins constitute an expanding family, members of which carry two conserved motifs named the BTB/POZ and the kelch repeat domains. The best-characterized member, Drosophila Kelch, constitutes the ring canals in the egg chamber in association with actin. However, physiological and biochemical functions of the members of this family remain largely uncharacterized.
Results: We identified the kel-1 gene encoding a Kelch-related protein in the nematode Caenorhabditis elegans. The deduced KEL-1 protein had 618 amino acid residues and was most similar to Drosophila Kelch. Loss of kel-1 function caused growth arrest at an early larval stage, most likely at the beginning of L2. The kel-1 deletion mutant appeared normal in morphology, movement and pumping action for the initial two to three days after hatching, but it failed to convey foods effectively to intestine and could hardly increase in body size. Analyses using immunostaining and reporter gene expression indicated that kel-1 was expressed almost exclusively in the g1 pharyngeal gland cells during late embryogenesis and at all developmental stages thereafter.
Conclusions: C. elegans KEL-1 protein is essential for the larval development, probably performing a function required for feeding in the pharyngeal g1 gland cells, which are supposed to secrete materials aiding digestion.