FIG. 3.

Time course of the hypo-osmotic shock response in P. pastoris expressing TIP3;1-G₃-H₆ and wild-type yeast. Differences in the optical absorbance between recombinant (A) and wild-type (B) yeast spheroplasts resulting from hypo-osmotic shock correspond to the start of TIP3;1-G₃-H₆ aquaporin expression, shown by SDS-PAGE and Western immunoblotting of yeast spheroplasts using PvTIP3;1 antisera (C). The primary immunolabeled protein has a molecular weight (MW) of ∼25,000, which agrees well with the predicted MW of 28,200 for the TIP3;1-G₃-H₆ monomer and is typical of PvTIP3;1 during SDS-PAGE (22, 23). Optical absorbance was measured ∼10 s following the osmotic shock. In performing the assay, there is a lapse of 2 h between culture sampling and the application of the osmotic shock.