The epithelial-specific adaptor AP1B mediates post-endocytic recycling to the basolateral membrane

Abstract

To perform vectorial secretory and transport functions that are critical for the survival of the organism, epithelial cells sort plasma membrane proteins into polarized apical and basolateral domains1,2. Sorting occurs post-synthetically, in the trans Golgi network (TGN) or after internalization from the cell surface in recycling endosomes, and is mediated by apical and basolateral sorting signals embedded in the protein structure3,4. Basolateral sorting signals include tyrosine motifs in the cytoplasmic domain that are structurally similar to signals involved in receptor internalization by clathrin-coated pits5,6. Recently, an epithelial-specific adaptor protein complex, AP1B, was identified7,8. AP-1B recognizes a subset of basolateral tyrosine motifs through its μ1B subunit7,8. Here, we characterized the post-synthetic and post-endocytic sorting of the fast recycling low density lipoprotein receptor (LDLR) and transferrin receptor (TfR) in LLC-PK1 cells, which lack μ1B and mis-sort both receptors to the apical surface8. Targeting and recycling assays in LLC-PK1 cells, before and after transfection with μ1B, and in MDCK cells, which express μ1B constitutively, suggest that AP1B sorts basolateral proteins post-endocytically.

Cite this article

Gan, Y., McGraw, T. & Rodriguez-Boulan, E. The epithelial-specific adaptor AP1B mediates post-endocytic recycling to the basolateral membrane. Nat Cell Biol 4, 605–609 (2002). https://doi.org/10.1038/ncb827

View full text

>> Full Text:   The epithelial-specific adaptor AP1B mediates post-endocytic recycling to the basolateral membrane