Fig. 3. Structural insights into binding of phospho-peptides to βarr1.

a Structural snapshots comparing the relative orientation and local interaction networks of trypsin cleavage sites Arg¹⁸⁸ and Arg²⁸⁵ in the crystal structures of βarr1 in basal (PDB: 1G4M, grey), V₂Rpp^WT-bound (PDB: 4JQI, orange) and V₂Rpp^T360-1-bound (PDB: 7DFA, violet) conformations. The dotted lines represent hydrogen bonds and polar interactions. b Molecular dynamics simulations based on the crystal structures confirm an overall similar conformational space sampled by Arg¹⁸⁸ and Arg²⁸⁵, the two trypsin proteolysis sites which are protected by ScFv30.