Fig. 5.

Cab45 is essential for apical sorting of GPI-APs. (A) N&B analysis of GFP-FR in the Golgi of polarized scrambled and Cab45-silenced MDCK cells. Quantification of the brightness of GFP-FR in the Golgi compartment from three independent experiments either in CTRLi (red bar) or Cab45i (blue bar) clones. (B) CTRLi and Cab45i cells grown for 3 d on a coverslip were subjected to a temperature block assay as described in Fig. 3C. Representative images taken at the top and at the middle of the cells are shown. Pearson’s coefficient between GFP-FR and giantin/furin is shown as mean of three different experiments (CTRLi, cyan bars; Cab45i, blue bars). (Scale bars, 4 μm.) (C) MDCK:GFP-FR CTRLi or Cab45i cells grown for 4 d on a filter were imaged in live conditions or stained with anti-GP114 antibody. Mean fluorescence intensities at the apical and basolateral surface were measured and expressed as percentages of the total fluorescence. (Scale bars, 6 μm.) Error bars, ± SD. NS, not significant; *P < 0.05; **P < 0.01; ***P < 0.001, Student’s t test.