Figure 4.

A simplified four-point model can well describe domain motion in the complex. (A) The four-point model represents NHERF1·FERM, with centers of PDZ1, PDZ2, CT, and FERM taken from Fig. 3A. (B) Comparing experimental D_eff(Q) with the four-point rigid-body calculations for NHERF1·^hFERM (blue open squares are experimental and blue solid line is calculation) and for NHERF1·^dFERM (red open squares, experimental and red solid line, calculation). D₀ of NHERF1·^dFERM (solid red squares) and NHERF1·^dFERM (solid blue squares) are shown. (C) Comparing experimental data with calculations assuming interdomain motion between PDZ1 and PDZ2 in NHERF1·^dFERM (red dashed line) and NHERF1·^hFERM (blue dashed line). Experimental symbols same as in panel B. (D) Comparing the experimental data with calculations incorporating interdomain motion between PDZ1 and PDZ2, as well as assuming a form factor of spheres of 20 Å radius for FERM and both PDZ domains in NHERF1·^dFERM (red dash-dot line) and in NHERF1·^hFERM (blue dash-dot line).