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. 2008 Dec 5;283(49):33889–33892. doi: 10.1074/jbc.M803865200

FIGURE 2.

FIGURE 2.

Effects of decreased cytosolic pH on water permeability of intact yeast protoplasts expressing native or mutant NtPIP2;1. Kinetics of protoplast swelling was recorded as time courses of decreased scattered light intensity (arbitrary units) in a stopped flow spectrophotometer. Yeast protoplasts expressing no extra aquaporin exhibit very low water permeability rates (upper three curves in a chart), whereas those expressing NtPIP2;1 completed swelling in 0.2 s following osmotic shift. A change of cytosolic pH was achieved by incubation of yeast spheroblasts expressing unaltered NtPIP2;1 (A) or mutant NtPIP2;1-S118A (B), NtPIP2;1-S277A (C), NtPIP2;1-H196A (D), or NtPIP2;1-H196A/S277A NtPIP2;1 (E) in buffers at pH 7.5 and pH 5, respectively, and an additional acid load treatment with 50 mm NaAc at pH 5. (n = 30 ± S.E.).