Figure 5.

Functional reconstitution of water transport activity in GlpF and AqpZ proteoliposomes. GlpF, AqpZ, or no protein was mixed with pure phospholipid and proteoliposomes were formed. A 2-fold osmotic gradient was imposed by rapidly mixing 100 μl of proteoliposome suspension (1 μg of protein) with an equal volume of hyperosmotic solution containing sucrose as a nonpermeant osmolyte in a stopped-flow apparatus. Water efflux causes vesicle shrinkage, which was measured by light scattering. The average kinetics of 5–10 measurements was normalized and fitted to a characteristic single-order exponential equation dependent on the time course of water efflux. Notice the different time scales in plots.