Previous studies have shown that ezrin binding to the scaffolding proteins NHERF1, allosterically activates the PDZ domains of NHERF1 to interact with target proteins. Biochemical and cell biological studies have shown that phosphorylation of NHERF1 reduces the ability of NHERF1 to assemble protein complexes in cells. Here we propose to use NSE to determine the effects of phosphorylation of S339 and S340 on the domain motion in NHERF1 and in the NHERF1∙Ezrin complex