FIGURE 4.

SAXS data and models. A, upper curves, comparison of the experimental SAXS pattern with the calculated profile of the symmetric trimer and the trimer from the asymmetric unit of the crystal; lower curves, fits of the rigid body model and the ab initio model to the experimental data. (The SAXS pattern of the upper curve was duplicated and shifted by −1 log I unit to facilitate presentation of multiple curves in one plot.) s, momentum transfer; I, scattered intensity. B, symmetric trimer from the crystal structure embedded into the three-dimensional profile of the ab initio model (gray beads) derived from the experimental data. C, symmetric trimer from the crystal structure (red) superimposed onto the rigid body model (blue) derived from the SAXS data using the monomeric subunit and P3 symmetry.