Figure 8.

Role of specific residues in the sea bream Aqp1b C-terminal tail for intracellular trafficking in oocytes. (A) Water permeability of oocytes expressing wild-type (WT) or mutant Aqp1b. Oocytes were injected with cRNAs encoding WT Aqp1b (0.25 or 1 ng), Aqp1b-T229A (1 ng), Aqp1b-L234A/L235A (1 ng), Aqp1b-S254A (0.25 ng) or Aqp1b-S254D (0.25 ng). Permeability is expressed in % related to oocytes injected with WT Aqp1b. Values are the mean ± SEM of 3–5 experiments (n = 10–15 oocytes per treatment). The asterisks denote statistically significant differences (*, p < 0.05; **, p < 0.01). (B-E) Immunoblots of total and plasma membrane equivalents (TM and PM, respectively) of oocytes expressing WT or mutant Aqp1b. The apparent molecular mass of a 29-kDa marker is indicated on the left. (F-J) Localization of Aqp1b mutants in oocytes. The plasma membrane is indicated by arrows, and retention of Aqp1b-L234A/L235A proteins possibly in the ER is indicated by arrowheads (H). Bars, 100 μm.