Extended Data Fig. 7: RAMP1 makes extensive stable interactions with CLR.

a, Hydrogen bonds between RAMP1 and CLR during molecular dynamics simulations (6.4 μs). The total persistence is plotted onto the experimental structure according to a rainbow colour scale, with residues that are never involved in dark blue and residues that are highly involved in red. The receptor is shown as a bulky ribbon, RAMP1 as a thin coloured ribbon and the peptide as a thin white ribbon. Key side chains are shown, but for intermittent hydrogen bonds the rotameric state has been modified to show an interaction. Residues forming an interaction network are labelled with the same colour. Left, overall topology of the system. Right top, magnified view of the upper portion of the CLR transmembrane domain and ECD; right bottom, view rotated by 90° on the z axis. Hydrogen bonds involved in the RAMP1–CLR interaction, R112^R–E47^ECD and D113^R–T288^ECL2/H289^ECL2 are notable because they link the transmembrane domain to the ECD, and for stabilizing ECL2. Other hydrogen bonds implicated in stabilizing the CLR and RAMP1 ECD interaction include S107^R–E47^ECD, R102^R–D55^ECD, H97^R–Q50^ECD, D90^R–Y49^ECD, D71^R–R38^ECD and E29^R–R119^ECD. Quantitative data on the persistence of hydrogen bonds during the simulations are reported in Supplementary Table 2. b, Contacts between RAMP1 and CLR during simulations (6.4 μs). The total persistence of a residue side chain is plotted onto the experimental structure according to a cyan–maroon colour scale, with residues that are never involved in cyan and residues that are highly involved in maroon. The peptide (italics, dashed line) is depicted as a thin ribbon, whereas the receptor (solid line) is shown as a bulky ribbon and transparent surface. Left, overall topology of the system. Top right, the most-persistent interactions involving RAMP residues and the CLR ECD, W59^R, I63^R, Y66^R, H97^R and I106^R help to anchor αH3 and the C-terminal RAMP1 regions of αH2 to (residues M42^ECD, T43^ECD, Y46^ECD, Y49^ECD, Q50^ECD and M53^ECD of the CLR ECD). Bottom right, the most-persistent hydrophobic interactions between the transmembrane domains of RAMP1 and CLR, namely I123^R, P126^R, T130^R, T134^R and V137^R (plus S141^R) help to anchor the RAMP transmembrane helix to CLR (TM3–TM5; CLR residues Y277^ECL2, H289^ECL2, A300^5.45, I235^3.52, F262^4.52, L258^4.48 and W254^4.44).