The role of structural dynamics in GPCR‐mediated signaling

G protein-coupled receptors (GPCRs) are the most intensively studied drug targets, largely due to their substantial involvement in human pathophysiology and their pharmacological tractability. Here, we report the first analysis of all GPCR drugs and agents in clinical trials. This reveals the current trends across molecule types, drug targets and therapeutic indications, including showing that 481 drugs (~34% of all drugs approved by the FDA) act at 107 unique GPCR targets. Approximately 320 agents are currently in clinical trials, of which ~36% target 64 potentially novel GPCR targets without an approved drug, and the number of biological drugs, allosteric modulators and biased agonists has grown. The major disease indications for GPCR modulators show a shift towards diabetes, obesity, and Alzheimer’s disease, while other central nervous system disorders remain highly represented. The 227 (57%) non-olfactory GPCRs that are yet to be explored in clinical trials have broad untapped therapeutic potential, particularly in genetic and immune system disorders. Finally, we provide an interactive online resource to analyse and infer trends in GPCR drug discovery.

The impact of molecular dynamics (MD) simulations in molecular biology and drug discovery has expanded dramatically in recent years. These simulations capture the behavior of proteins and other biomolecules in full atomic detail and at very fine temporal resolution. Major improvements in simulation speed, accuracy, and accessibility, together with the proliferation of experimental structural data, have increased the appeal of biomolecular simulation to experimentalists—a trend particularly noticeable in , though certainly not limited to, neuroscience. Simulations have proven valuable in deciphering functional mechanisms of proteins and other biomolecules, in uncovering the structural basis for disease, and in the design and optimization of small molecules, peptides, and proteins. Here we describe in practical terms the types of information MD simulations can provide and the ways in which they typically motivate further experimental work.

G protein-coupled receptors (GPCRs) are responsible for the majority of cellular responses to hormones and neurotransmitters as well as the senses of sight, olfaction and taste. The paradigm of GPCR signaling is the activation of a heterotrimeric GTP binding protein (G protein) by an agonist-occupied receptor. The β2 adrenergic receptor (β2AR) activation of Gs, the stimulatory G protein for adenylyl cyclase, has long been a model system for GPCR signaling. Here we present the crystal structure of the active state ternary complex composed of agonist-occupied monomeric β2AR and nucleotide-free Gs heterotrimer. The principal interactions between the β2AR and Gs involve the amino and carboxyl terminal α-helices of Gs, with conformational changes propagating to the nucleotide-binding pocket. The largest conformational changes in the β2AR include a 14 Å outward movement at the cytoplasmic end of transmembrane segment 6 (TM6) and an alpha helical extension of the cytoplasmic end of TM5. The most surprising observation is a major displacement of the alpha helical domain of Gαs relative to the ras-like GTPase domain. This crystal structure represents the first high-resolution view of transmembrane signaling by a GPCR.