The Caenorhabditis elegans gene lin-17, which is required for certain asymmetric cell divisions, encodes a putative seven-transmembrane protein similar to the Drosophila frizzled protein.

Mutations in the gene lin-1 7 result in the disruption of a variety of asymmetric cell divisions in Caenorhabditis elegans. We have found that lin-1 7 encodes a protein with seven putative transmembrane domains. The LIN-17 protein is most similar to the Drosophila Frizzled protein and its vertebrate homologs. Studies using a lin-1 7-green fluorescent protein translational fusion indicate that lin-1 7 is expressed in mother cells before asymmetric cell divisions and in both daughter cells after the divisions. Our results suggest that lin-1 7 encodes a receptor that regulates the polarities of cells undergoing asymmetric cell divisions and raise the possibility that the LIN-17 protein acts as a receptor for the Wnt protein LIN-44, which also controls asymmetric cell divisions.