Fig. 4. Characterization of the anti-AQP2 C-loop antibody. (A) Western blots of membrane fractions from CD8 cells and from rat kidney. LS, low-speed pellet; HS high-speed pellet. (B) Immunolocalization of AQP2 in CD8 cells using either the anti-AQP2 raised against the peptide reproducing the C-terminus (AQP2 C-term) or the anti-AQP2 raised against the peptide reproducing the loop C (AQP2 C-loop). In non-permeabilized (-Triton X-100) forskolin-stimulated cells (FK), the anti-AQP2 C-loop stained the apical surface of the CD8 cells. Under the same experimental conditions, no fluorescence signal was observed using the anti-AQP2 C-term antibody. By contrast, both antibodies stained AQP2-containing intracellular vesicles in permeabilized control CD8 cells (+Triton X-100). Bar, 5 µm.