14-3-3η binding affects the mobility of Nedd4-2 WW domains. Fluorescence anisotropy decays of Nedd4-2 variants with AEDANS-labeled individual WW domains in the absence and presence of 14-3-3η. (A) WW1 domain variants C209 and C218, (B) WW2 domain variants C389 and C414, and (C) WW3 and WW4 domain variants C508, C522, and C571. To see this figure in color, go online.