Mean fluorescence lifetimes of Nedd4-2 variants and their changes upon 14-3-3η binding. The positions of AEDANS-labeled cysteine residues within Nedd4-2 domains are indicated at the bottom. C209 and C218, WW1; C389 and C414, WW2; C414 and C508, WW3; C571, WW4; C943, the C-lobe of HECT domain. Each error bar reflects the standard deviation of a single-curve data analysis.