Fig. 7. DdRab11 co-localizes with the calmodulin and RabD, but not the 100 kDa proton pump subunit in cells exposed to hyper-osmotic conditions. Cells growing on coverslips in HL5 were exposed to sucrose (100 mM) in HL5 for 1 hour. Cells were fixed with formaldehyde and decorated with antibodies to DdRab11 (A,E), RabD (C), calmodulin (B,D) and the proton pump subunit (F). Cells were visualized using a fluorescence microscope. White arrows denote a contractile membrane structure that contains DdRab11 and calmodulin proteins (A,B) and RabD and calmodulin (C,D). DdRab11 protein was found in reticular contractile vacuolar membranes when compared with the ATPase-positive vesicular structures accumulating in cells exposed to hyper-osmotic conditions. The white arrow shows the ATPase-positive DdRab11-negative region (F). Scale bar: 5 µm.