Stopped-flow assays for measurement of water transport activity of <i>V. vinifera</i> aquaporins expressed in yeast.

<p>(A) Typical traces obtained from stopped-flow spectroscopy after hyperosmotic shock. Presented signals are illustrative of ten traces at 23°C obtained from strains expressing functional (<i>Vv</i>TnPIP2;1) and non-functional (<i>Vv</i>TnTIP4;1) aquaporins for water transport, and control (transformed with empty plasmid pUG35). (B) Water permeability coefficients (<i>P<sub>f</sub></i> at 23°C) of <i>Vv</i>TnPIP2;1, <i>Vv</i>TnTIP1;1 and <i>Vv</i>TnTIP2;2 were higher than control strain. Expression of <i>Vv</i>TnPIP1;4, <i>Vv</i>TnPIP2;3 and <i>Vv</i>TnTIP4;1 did not increase water permeability in yeast cells. Data are mean ± SD of three independent experiments with at least ten traces.</p>