Fig. 8.

Model for interaction of Wg and DFz2 in the wing disc Wg and DFz2 are internalized from different surfaces of the polarized wing epithelium via distinct endocytic pathways. Wg interacting with its putative receptor at the apical surface is directed toward the CG pathway, regulated by Arf1, Garz, and class I PI3K, and DFz2 is internalized from the basolateral surface via the CD pathway. The resulting endosomes fuse and the acidification of these endosomes facilitates the interaction of Wg and DFz2. Subsequently, the signal transducers of the Wg–DFz2 assemble at the endosomal membrane and initiate signaling.