Expression of ARH(R266A) specifically interrupts exocytosis of LDLR-CT27. Filter-grown MDCK cells were co-injected with cDNAs encoding V5-tagged ARH(R266A) and LDLR-CT27 (A), LDLR(Y18A) (B), or VSVG (C). Cells were subjected to cell surface staining using cargo-specific antibodies, fixed, and permeabilized to stain for total cargo (A and B) and ARH(R266A)-V5. Specimens were analyzed by confocal microscopy and representative xz sections are shown. Bars, 5 µm.