A C. elegans CLIC-like Protein Required for Intracellular Tube Formation and Maintenance

The Caenorhabditis elegans excretory canal is composed of a single elongated and branched cell that is tunneled by an inner lumen of apical character. Loss of the exc-4 gene causes a cystic enlargement of this intracellular tube. exc-4 encodes a member of the chloride intracellular channel (CLIC) family of proteins. EXC-4 protein localizes to various tubular membranes in distinct cell types, including the lumenal membrane of the excretory tubes. A conserved 55–amino acid domain enables EXC-4 translocation from the cytosol to the lumenal membrane. The tubular architecture of this membrane requires EXC-4 for both its formation and maintenance.