Aquaporins andaquaglyceroporinsmediate the transport of waterand cerevisiaeFps1 is an aquaglyceroporin that mediates controlled glycerol export during osmoregulation. The transport function of Fps1 is rapidly regulated by osmotic changes in an apparently unique way and distinct regions within the longN-andC-terminal extensions are needed for this regulation. Inorder to learnmoreabout themechanisms that control Fps1 we have set up a genetic screen for hyperactive Fps1 and isolated mutations in 14 distinct resi-dues, all facing the inside of the cell. .
