Fig. 3.

Interhelical polar contacts at the cytoplasmic face of β₁AR–M23. (A) The structure of the bent conformation is depicted, with the intact ionic lock between Arg139 and Glu285. (B) The structure of the straight conformation is shown, with the ionic lock broken. Structures are shown as cartoons in rainbow coloration (N terminus in blue, C terminus in red), except for CL2 and the cytoplasmic extension of H6 which are in gray and residues predicted to form interhelical hydrogen bonds shown as sticks.