Rab8a and Rab11a binding of Myo5B is important for its proper function. (A) Sec15 and Stx3 interaction is reduced in Rab11a and Rab8a/11a binding–deficient mutants of Myo5B. Strep-Tactin was used for coaffinity purification (co-AP). (B) Rab binding–deficient mutants of Myo5B fail to rescue the brush border defects (arrows) and the subapical accumulation of vesicles (arrowheads) in Myo5B-depleted cells. Bars, 1 µm. (C) Quantification of single lumen formation shows that Rab binding–deficient mutants of Myo5B fail to rescue the polarity defect upon Myo5B depletion. Mean ± SD. ***, P < 0.005. n ≥ 100 cysts/experiment; three independent experiments.