Figure 3.

Activation of domain motion in NHERF1 upon binding to FERM domain. (A) The three-dimensional shape of NHERF1·FERM reconstructed from SANS (14) using the software MONSA (30). The structures of PDZ1, PDZ2, and ezrin FERM (PDB code: 1NI2) are docked into the envelope. Arrows represent motions between PDZ1 and PDZ2. A 60 Å scale bar is shown. (B) Comparing experimental D_eff(Q) with rigid-body calculations for NHERF1·^dFERM (open red squares and solid red line) and NHERF1·^hFERM (open blue squares and blue line). Rigid-body calculations used the dummy-atom coordinates from SANS (14). D₀ for NHERF1·^dFERM (solid red squares) and NHERF1·^hFERM (solid blue squares) are from PFG NMR. D₀ (solid black squares), D_eff(Q) (open black squares), and the rigid-body calculation (solid black line) of NHERF1 are shown. (C) Comparing NSE data with rigid model calculations for the NHERF1·^dFERM and NHERF1·^hFERM complexes using the coordinates of the docked domains. Symbols same as in panel B. (D) Comparing experimental D_eff(Q) with calculations incorporating interdomain motion (via the mobility tensor) between PDZ1 and PDZ2, for NHERF1·^dFERM (dashed red line), and NHERF1·^hFERM (dashed blue line). Calculations used the docked structures. Symbols for D_eff(Q) and D₀ same as panels B and C.