SAXS analysis of Lu gp D1D2D3. (A) Experimental scattering data for Lu gp D1D2D3 plotted in black as a function of q and compared with a theoretic fit generated with SASREF.46 (B) Shapes obtained using a bead model using the program GASBOR47 from 20 independent simulations, each differently colored. The average shape is shown as orange wire-frame density in (C) representative rigid-body fit of the D1D2 crystal structure and D3 model to the scattering data, overlaid on average density obtained as in panel B. D1 is shown in blue; D2, green; and D3, red. (D) Shapes obtained from the scattering curve for Lu gp (D1-D5) as described in panel B. The average shape is shown as orange wire-frame density in (E) overlay of the D1D2D3 model on the envelope derived for Lu gp (D1-D5). D4 and D5 are expected to occupy the additional density at the base of the figure, proximal to the cell membrane.