Deletion of the cytoplasmic domain of the polymeric immunoglobulin receptor prevents basolateral localization and endocytosis.

We deleted the cytoplasmic domain of the polymeric immunoglobulin receptor. When expressed in fibroblasts, the truncated receptor, like the wild-type, reaches the cell surface, can bind ligand, and is cleaved to secretory component. Unlike the wild-type, it is not endocytosed. When expressed in polarized Madin-Darby canine kidney cells, the mutant receptor is transported from the Golgi apparatus directly to the apical surface and cleaved to secretory component. In contrast, the wild-type receptor travels from the Golgi to the basolateral surface and is then endocytosed and sent to the apical surface. These results suggest that the cytoplasmic domain of the receptor is necessary for both basolateral localization and endocytosis.