Superpositions of CGRPmut-bound and ligand-free CLR:RAMP1 complexes (ter Haar et al., 2010) revealed clamp-like movement of CLR loops 3 and 4 upon CGRPmut binding, presumably mediated by the CGRPmut T30-CLR D94 interaction and β-turn contacts with CLR loop 4 including the CGRPmut F35-CLR S117 interaction (Figures 3A and 3B). CLR R119 shifts to accommodate the peptide and RAMP1 F83 rotates away from CLR loop 4 (Figure 3B). The RAMP1 position relative to CLR varies in the structures (Figure 3A), but the positions of the α2-α3 loop and W84, which contacts CGRPmut F37, remain relatively similar (Figures 3A and 3B).