Rabaptin-5 knock-down decreases surface FcϵRIα expression in BMCMCs. (A) Surface FcϵRIα expression was analyzed by flow cytometry on control (shC) or Rabaptin-5 (shR) shRNA-treated BMCMCs. Representative histograms comparing control (black filled histogram) and Rabaptin-5-deficient (unfilled histogram) BMCMCs. Gray filled histogram indicates streptavidin only. Bar graph depicts surface expression of the indicated mast cell receptors assayed by flow cytometry, pooled from 5 different pairs of shC- or shR-treated BMCMCs. (B) Total or surface FcϵRIα levels from control or Rabaptin-5–deficient BMCMCs were analyzed by flow cytometry. Bar graph indicates total FcϵRIα expression relative to shC-treated BMCMCs from 5 separate experiments. (C) The subcellular distribution of FcϵRIα in shC- or shR-treated BMCMCs was assessed by confocal microscopy as described in Document S1, “Immunofluorescence.” Bar represents 7.5 μm. (D) Localization of Rab5 (green), Rabaptin-5 (red), and FcϵRIα (blue) was examined in control BMCMCs by confocal microscopy. Magnified images of the regions outlined by dashed boxes are shown in the upper right corner of each panel. Bar represents 7.5 μm. In panels A and B: +P < .05, ++P < .01, +++P < .001, compared with hypothetical value of 100.