Contextual Binding of p120 ctn to E-cadherin at the Basolateral Plasma Membrane in Polarized Epithelia

• Published in: The Journal of biological chemistry Vol. 278; no. 44; pp. 43480 - 43488
• Main Authors: Miranda, Kevin C., Joseph, Shannon R., Yap, Alpha S., Teasdale, Rohan D., Stow, Jennifer L.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 31.10.2003
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M305525200

E-cadherin-catenin complexes mediate cell-cell adhesion on the basolateral membrane of epithelial cells. The cytoplasmic tail of E-cadherin supports multiple protein interactions, including binding of β-catenin at the C terminus and of p120 ctn to the juxtamembrane domain. The temporal assembly and polarized trafficking of the complex or its individual components to the basolateral membrane are not fully understood. In Madin-Darby canine kidney cells at steady state and after treatment with cycloheximide or temperature blocks, E-cadherin and β-catenin localized to the Golgi complex, but p120 ctn was found only at the basolateral plasma membrane. We previously identified a dileucine sorting motif (Leu586-Leu587, termed S1) in the juxtamembrane domain of E-cadherin and now show that it is required to target full-length E-cadherin to the basolateral membrane. Removal of S1 resulted in missorting of E-cadherin mutants (EcadΔS1) to the apical membrane; β-catenin was simultaneously missorted and appeared at the apical membrane. p120 ctn was not mistargeted with EcadΔS1, but could be recruited to the E-cadherin-catenin complex only at the basolateral membrane. These findings help define the temporal assembly and sorting of the E-cadherin-catenin complex and show that membrane recruitment of p120 ctn in polarized cells is contextual and confined to the basolateral membrane.