Comparison of apo LAP and TGFβ-1 bound (LTGFβ-1) structures. Only residues modelled in the apo structure were included for comparison. The apo structure reported here (blue; PDB entry 6p7j) is aligned with pig TGFβ-1 bound LAP (yellow; PDB entry 3rjr; Shi et al., 2011). (a) The side view shows that the inter-monomer angle in the apo structure is 15° greater than that in the bound structure. For clarity, the blob diagram approximates this movement of the arm domains. The angle measured here reflects the shift of one monomer in the bound structure relative to the same monomer in the apo structure. (b) Front orientation of the alignment. RGD indicates the integrin-binding motif. (c) A close-up view of the RGD-containing loop shows that it is similarly positioned in both structures, on the solvent-exposed shoulder of the arm domain. For clarity, the Cα atoms of Gly and Asp (which are modelled in both structures) from the motif are shown as spheres.