Dynamic allosteric networks drive adenosine A1 receptor activation and G-protein coupling

G-protein coupled receptors (GPCRs) present specific activation pathways and signaling among receptor subtypes. Hence, an extensive knowledge of the structural dynamics of the receptor is critical for the development of therapeutics. Here, we target the adenosine A₁ receptor (A₁R), for which a negligible number of drugs have been approved. We combine molecular dynamics simulations, enhanced sampling techniques, network theory, and pocket detection to decipher the activation pathway of A₁R, decode the allosteric networks, and identify transient pockets. The A₁R activation pathway reveals hidden intermediate and pre-active states together with the inactive and fully-active states observed experimentally. The protein energy networks computed throughout these conformational states successfully unravel the extra and intracellular allosteric centers and the communication pathways that couple them. We observe that the allosteric networks are dynamic, being increased along activation and fine-tuned in the presence of the trimeric G-proteins. Overlap of transient pockets and energy networks uncovers how the allosteric coupling between pockets and distinct functional regions of the receptor is altered along activation. Through an in-depth analysis of the bridge between the activation pathway, energy networks, and transient pockets, we provide a further understanding of A₁R. This information can be useful to ease the design of allosteric modulators for A₁R.