Figure 6. Water permeability of AQP0 expressed in Xenopus oocytes. The osmotic water permeability (Pf) of AQP0 expressed on Xenopus oocyte membranes was determined by measuring the change in oocyte diameter. To balance the loading of ribosomes and obtain the same amount of transcribed AQP0 in each reaction, 12.5 ng cRNA of GST was co-injected as a blank with 12.5 ng cRNA of AQP0 (AQP0+GST). The water permeability was reduced when Xenopus oocytes were co-injected with 12.5 ng filensin COOH-terminal peptide cRNA and 12.5 ng of AQP0 cRNA, however, there was no significant difference between the water permeability value for AQP0+GST and the value obtained when 12.5 ng filensin rod domain cRNA was co-injected with 12.5 ng AQP0 (AQP0+fil rod) cRNA. These results suggested that the filensin tail region interacted with AQP0 to reduce the water permeability of AQP0, while the filensin rod peptide had no effect.