In order to investigate the importance of the protein-ligand interaction differences between I942 and cAMP outlined above, I942 was remodelled with weak flat-bottom distance restraints applied between I942-K353 (lid region) and I942-G269 (PBC), to mimic the hydrogen bonds seen with cAMP (Supplementary Figure ). Although the restraints to the lid that correspond to the "in" conformation, indicating that tightening interactions between I942 and G269 is indeed sufficient to fully shift the PBC conformation from the "out" to the "in" conformation. This PBC rearrangement is sufficient to partially disrupt the ionic latch (Supplementary Figure ). The hinge region RMSF values are similar when only the PBC or the lid restraints are applied. This shows that the PBC shift from an "out" to an "in" conformation is sufficient to allow melting of the hinge. However the lower active state probabilities observed when only PBC restraints are applied suggest that additional lid-ligand interactions are necessary to stabilise the active state conformation.