Impact of G protein-coupled receptor conformation on signaling bias: Integrating simulations and biophysical experiments

G protein-coupled receptors (GPCRs) are a ubiquitous family of transmembrane proteins essential for signal transduction and serve as key targets for numerous drug classes. A single GPCR often mediates multiple, largely independent pathways, which can sometimes be selectively modulated by biased ligands that preferentially activate specific signaling routes. These molecules stabilize distinct receptor conformations, with even subtle structural variations capable of driving different cellular responses. Capturing the conformations responsible for biased signaling, however, often proves challenging with traditional experimental techniques. Recent advances in experimental methods, coupled with computational modeling, have shed new light on the structural mechanisms underlying biased signaling. This review highlights therapeutically relevant examples, focusing on mechanisms such as (i) partial occupation of the orthosteric pocket, resulting in submaximal activation, and (ii) binding to alternative sites via bitopic or allosteric compounds. Emphasis is placed on studies that integrate biophysical and computational approaches, demonstrating their synergistic potential to unravel the complexities of GPCR signaling. This combined strategy paves the way for the rational design of innovative drugs with greater precision and therapeutic efficacy.