Figure 3.

Immunolocalization of OCTN1 and OCTN2 proteins in human airway epithelial cells grown and re-differentiated in ALI cultures. To identify cellular localization of the pH-dependent organic cation transporters, epithelial cultures were double-labeled with antibodies to OCTN1, OCTN2, or nonimmune IgG (negative control) (green) and acetylated tubulin (red) for analysis with confocal laser scanning microscopy. Samples were mounted in a reagent containing DAPI to stain nuclei (blue). Images are z-axis reconstructions of OCTN1 (A), OCTN2 (B), and acetylated tubulin expression (D–F); overlay z-axis reconstructions (G–I); and overlay confocal images at the level of the cilia (J–L). Images demonstrate OCTN1 and OCTN2 expression in the apical/subapical portion of the cells. Overlay images reveal co-localization of OCTN2 and acetylated tubulin (H and K) indicating OCTN2 protein expression in cilia of airway epithelial cells.