SAXS-based rigid-body modelling and clustering shows that most apo LAP models include a reorientation of the inter-monomer position compared with the TGFβ-1 bound LAP crystal structure. (a) CORAL models from cluster 1 (gradient from yellow to red illustrating the magnitude of inter-monomer rotation relative to the bound LAP structure) and the apo LAP structure (blue) superimposed onto a single chain of bound LAP (grey/black). For clarity, models are shown without the straight-jacket domain [entire models are shown in Supplementary Fig. S3(b)]. (b) CORAL models from cluster 2 (red and gold) and the apo LAP structure (blue) superimposed onto a single chain of bound LAP (grey/black), indicating rotation (left) and displacement (right) relative to the bound LAP structure. (c) Comparison of the average theoretical scattering of models within each cluster with the experimental scattering data (top) with residuals (bottom).