Figure 2. Relative orientations of the receptors in the dimer state.

Normalized population of the relative orientations of the two receptors in the dimer regime defined by the angles θ₁ and θ₂ (see Methods for details). The populations were averaged over the dimer regime for simulations in (a) POPC bilayers and POPC/cholesterol bilayers with (b) 9 (c) 30 and (d) 50% cholesterol concentrations. The relative orientations can be broadly mapped to four conformations (A, B, C and A′) that are marked in panels (a–d). The four conformations correspond to two sites at the receptor: site 1 comprising of transmembrane helices I and II and site 2 comprising of transmembrane helices IV, V and VI. (e) Conformation A corresponds to a non-flexible homo-interface with only a single helix from site 1 (transmembrane helix I). (f) Conformation B corresponds to homo-interfaces at site 2. (g) Conformation C corresponds to hetero-interfaces comprising of transmembrane helices from sites 1 and 2. (h) Conformation A′ corresponds to a flexible interface at site 1.