FIG. 7.

The EEDE cluster and the FI motif are required for basolateral sorting in the context of the complete furin tail. MDCK cells expressing TTF FI→AA (a and b), TTF Y758A (c and d), TTF EEDE→AAAA (e and f), or TTF Y758A, EEDE→AAAA (g and h) were grown as polarized cell monolayers and incubated at 37°C for 30 min with anti-Tac antibody added to the upper (panels a, c, e, and g) or lower (panels b, d, f, and h) compartment. Cells were then washed on ice, fixed, and permeabilized, and anti-Tac antibodies were visualized by using a labeled second antibody. Mutations affecting either the FI motif or the EEDE motif in TTF FI→AA, TTF EEDE→AAAA, or TTF Y758A, EEDE→AAAA lead to impaired basolateral sorting (panels a, b, and e through h); inactivating the tyrosine-based endocytosis signal in TTF Y758A has no effect on basolateral transport (panels c and d). Bar, 10 μm.