Figure 2. Crystal packing of β₂AR (yellow) with crystallization chaperones (blue).

(a) Covalent chaperone (PDB code 2RH1) [92]. T4 lysozyme is inserted into the third intracellular loop (left). Four major crystal contacts occur in T4 lysozyme-β₂AR lattice, three of which involve T4 lysozyme (right). (b) Non-covalent chaperone (PDB code 2R4R) [98], utilizing a Fab fragment specific for the third intracellular loop (left). The Fab fragment mediates nearly all crystal contacts within the lattice containing the Fab-β₂AR complex (right).