title: A PDZ-binding motif controls basolateral targeting of syndecan-1 along the biosynthetic pathway in polarized epithelial cells.
abstract: The cell surface proteoglycan, syndecan-1, is essential for normal epithelial morphology and function. Syndecan-1 is selectively localized to the basolateral domain of polarized epithelial cells and interacts with cytosolic PDZ (PSD-95, discs large, ZO-1) domain-containing proteins. Here, we show that the polarity of syndecan-1 is determined by its type II PDZ-binding motif. Mutations within the PDZ-binding motif lead to the mislocalization of syndecan-1 to the apical surface. In contrast to previous examples, however, PDZ-binding motif-dependent polarity is not determined by retention at the basolateral surface but rather by polarized sorting prior to syndecan-1's arrival at the plasma membrane. Although none of the four known PDZ-binding partners of syndecan-1 appears to control basolateral localization, our results show that the PDZ-binding motif of syndecan-1 is decoded along the biosynthetic pathway establishing a potential role for PDZ-mediated interactions in polarized sorting.
authors.affiliation: Department of Cell Biology, Ludwig Institute for Cancer Research, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Sandra
authors.initials: S
authors.lastname: Maday
authors.forename: Eric
authors.initials: E
authors.lastname: Anderson
authors.forename: Henry C
authors.initials: HC
authors.lastname: Chang
authors.forename: James
authors.initials: J
authors.lastname: Shorter
authors.forename: Ayano
authors.initials: A
authors.lastname: Satoh
authors.forename: Jeff
authors.initials: J
authors.lastname: Sfakianos
authors.forename: Heike
authors.initials: H
authors.lastname: Fölsch
authors.forename: James M
authors.initials: JM
authors.lastname: Anderson
authors.forename: Zenta
authors.initials: Z
authors.lastname: Walther
authors.forename: Ira
authors.initials: I
authors.lastname: Mellman