Abstract
Growth factors and morphogens need to be secreted to act on distant cells during development and in response to injury. Here, we report evidence that efficient export of a fibroblast growth factor (FGF), EGL-17, from the Caenorhabditis elegans developing vulva requires the lipoprotein receptor-related proteins Ce-LRP-1 and Ce-LRP-2 and a cytoplasmic adaptor protein, Ce-DAB-1 (Disabled). Lipoprotein receptors are transmembrane proteins best known for their roles in endocytosis. Ce-LRP-1 and Ce-LRP-2 possess a conserved intraluminal domain that can bind to EGL-17, as well as a cytosolic FXNPXY motif that can bind to Ce-DAB-1. Ce-DAB-1 contains signals that confer subcellular localization to Golgi-proximal vesicles. These results suggest a model in which Ce-DAB-1 coordinates selection of receptors and cargo, including EGL-17, for transport through the secretory pathway.