AbstractTetrahydrocannabinol (THC) is the principal psychoactive compound derived from the cannabis plant Cannabis sativa and approved for emetic conditions, appetite stimulation and sleep apnea relief. THC’s psychoactive actions are mediated primarily by the cannabinoid receptor CB1. Here, we determine the cryo-EM structure of HU210, a THC analog and widely used tool compound, bound to CB1 and its primary transducer, Gi1. We leverage this structure for docking and 1000 ns molecular dynamics simulations of THC and 10 structural analogs delineating their spatiotemporal interactions at the molecular level. Furthermore, we pharmacologically profile their recruitment of Gi and β-arrestins and reversibility of binding from an active complex. By combining detailed CB1 structural information with molecular models and signaling data we uncover the differential spatiotemporal interactions these ligands make to receptors governing potency, efficacy, bias and kinetics. This may help explain the actions of abused substances, advance fundamental receptor activation studies and design better medicines.

G protein-coupled receptors are highly complex signal transduction proteins with many potential biomedical applications. Researchers from different fields work together to improve mechanistic understanding of GPCR function and to transfer that knowledge in order to advance therapeutic options. Due to the interdisciplinary nature of GPCR research, many databases and web tools with different types and levels of information are being developed to support scientists in sharing and analysing data. Here, we aim to give an overview of freely available online chemoinformatics and bioinformatics resources specifically designed to aid GPCR research. We compiled a dedicated domain on ELIXIR's bio. tools portal as a continuously updatable repository of GPCR-related online resources (https://bio.tools/t?domain=gpcr). This provides an up-to-date overview of available tools, rather than a static list representing only a snapshot in time. Furthermore, we give some recommendations for developing and using scientific online resources and briefly describe selected databases and web-based tools for GPCR research. LINKED ARTICLES: This article is part of a themed issue Complexity of GPCR Modulation and Signaling (ERNST). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v182.14/issuetoc.

G protein-coupled receptors (GPCRs) form one of the largest drug target families, reflecting their involvement in numerous pathophysiological processes. In this Review, we analyse drug discovery trends for the GPCR superfamily, covering compounds, targets and indications that have reached regulatory approval or that are being investigated in clinical trials. We find that there are 516 approved drugs targeting GPCRs, making up 36% of all approved drugs. These drugs act on 121 GPCR targets, one-third of all non-sensory GPCRs. Furthermore, 337 agents targeting 133 GPCRs, including 30 novel targets, are being investigated in clinical trials. Notably, 165 of these agents are approved drugs being tested for additional indications and novel agents are increasingly allosteric modulators and biologics. Remarkably, diabetes and obesity drugs targeting GPCRs had sales of nearly US $30 billion in 2023 and the numbers of clinical trials for GPCR modulators in the metabolic diseases, oncology and immunology areas are increasing strongly. Finally, we highlight the potential of untapped target-disease associations and pathway-biased signalling. Overall, this Review provides an up-to-date reference for the drugged and potentially druggable GPCRome to inform future GPCR drug discovery and development.

G protein-coupled receptors (GPCRs) have been targeted across all therapeutic areas, mediate the actions of 516 (36% of all) approved drugs and are being targeted by 337 agents in clinical trials. So far, 121 GPCRs are targets of approved drugs and 30 additional receptors have entered clinical trials and may expand the drugged GPCRome in the coming years. Here, we describe an online resource of GPCR drugs, clinical trial agents, targets and disease indications. This resource offers unique reference data, analysis and visualization, and is availed as a new section, ‘Drugs and Agents in trial’ integrated in the GPCR database, GPCRdb. Furthermore, it includes a target selection tool for prioritization of receptors for future drug discovery. This up-to-date knowledgebase will help identify strategies and trends in current GPCR drug discovery and give insights into which already drugged, or yet untapped targets have the largest potential in specific diseases.

G protein-coupled receptors (GPCRs) are the largest human membrane protein family that transduce extracellular signals into cellular responses. They are major pharmacological targets, with approximately 26% of marketed drugs targeting GPCRs, primarily at their orthosteric binding site. Despite their prominence, predicting the pharmacological effects of novel GPCR-targeting drugs remains challenging due to the complex functional dynamics of these receptors. Recent advances in X-ray crystallography, cryo-electron microscopy, spectroscopic techniques and molecular simulations have enhanced our understanding of receptor conformational dynamics and ligand interactions with GPCRs. These developments have revealed novel ligand-binding modes, mechanisms of action and druggable pockets. In this Review, we highlight such aspects for recently discovered small-molecule drugs and drug candidates targeting GPCRs, focusing on three categories: allosteric modulators, biased ligands, and bivalent and bitopic compounds. Although studies so far have largely been retrospective, integrating structural data on ligand-induced receptor functional dynamics into the drug discovery pipeline has the potential to guide the identification of drug candidates with specific abilities to modulate GPCR interactions with intracellular effector proteins such as G proteins and β-arrestins, enabling more tailored selectivity and efficacy profiles.

G protein-coupled receptors (GPCRs) constitute a functionally diverse protein family and are targets for a broad spectrum of pharmaceuticals. Technological progress in X-ray crystallography and cryogenic electron microscopy has enabled extensive, high-resolution structural characterisation of GPCRs in different conformational states. However, as highly dynamic events underlie GPCR signalling, a complete understanding of GPCR functionality requires insights into their conformational dynamics. Here, we present a large dataset of molecular dynamics simulations covering 60% of currently available GPCR structures. Our analysis reveals extensive local "breathing" motions of the receptor on a nano- to microsecond timescale and provides access to numerous previously unexplored receptor conformational states. Furthermore, we reveal that receptor flexibility impacts the shape of allosteric drug binding sites, which frequently adopt partially or completely closed states in the absence of a molecular modulator. We demonstrate that exploring membrane lipid dynamics and their interaction with GPCRs is an efficient approach to expose such hidden allosteric sites and even lateral ligand entrance gateways. The obtained insights and generated dataset on conformations, allosteric sites and lateral entrance gates in GPCRs allows us to better understand the functionality of these receptors and opens new therapeutic avenues for drug-targeting strategies.

The GPCR autoproteolysis inducing (GAIN) domain is an ancient protein fold ubiquitous in adhesion G protein-coupled receptors (aGPCR). It contains a tethered agonist necessary and sufficient for receptor activation. The GAIN domain is a hotspot for pathological mutations. However, the low primary sequence conservation of GAIN domains has thus far hindered the knowledge transfer across different GAIN domains in human receptors as well as species orthologs. Here, we present a scheme for generic residue numbering of GAIN domains, based on structural alignments of over 14,000 modeled GAIN domain structures. This scheme is implemented in the GPCR database (GPCRdb) and elucidates the domain topology across different aGPCRs and their homologs in a large panel of species. We identify conservation hotspots and statistically cancer-enriched positions in human aGPCRs and show the transferability of positional and structural information between GAIN domain homologs. The GAIN-GRN scheme provides a robust strategy to allocate structural homologies at the primary and secondary levels also to GAIN domains of polycystic kidney disease 1/PKD1-like proteins, which now renders positions in both GAIN domain types comparable to one another. In summary, our work enables researchers to generate hypothesis and rationalize experiments related to GAIN domain function and pathology.

The classical psychedelics (+)-lysergic acid diethylamide (LSD), psilocybin, and mescaline exert their psychedelic effects via activation of the 5-HT2A serotonin receptor (5-HT2AR). Recent clinical studies have suggested that classical psychedelics may additionally have therapeutic potential for many neuropsychiatric conditions including depression, anxiety, migraine and cluster headaches, drug abuse, and post-traumatic stress disorder. In this study, we investigated the pharmacology of 41 classical psychedelics from the tryptamine, phenethylamine, and lysergamide chemical classes. We profiled these compounds against 318 human G-protein-coupled receptors (GPCRs) to elucidate their target profiles, and in the case of LSD, against more than 450 human kinases. We found that psychedelics have potent and efficacious actions at nearly every serotonin, dopamine, and adrenergic receptor. We quantified their activation for multiple transducers and found that psychedelics stimulate multiple 5-HT2AR transducers, each of which correlates with psychedelic drug-like actions in vivo. Our results suggest that multiple molecular targets likely contribute to the actions of psychedelics.

Δ9-tetrahydrocannabinol (THC) is the principal psychoactive compound derived from the cannabis plant Cannabis sativa and approved for emetic conditions, appetite stimulation and sleep apnea relief. THC's psychoactive actions are mediated primarily by the cannabinoid receptor CB1. Here, we determine the cryo-EM structure of HU210, a THC analog and widely used tool compound, bound to CB1 and its primary transducer, Gi1. We leverage this structure for docking and 1,000 ns molecular dynamics simulations of THC and 10 structural analogs delineating their spatiotemporal interactions at the molecular level. Furthermore, we pharmacologically profile their recruitment of Gi and β-arrestins and reversibility of binding from an active complex. By combining detailed CB1 structural information with molecular models and signaling data we uncover the differential spatiotemporal interactions these ligands make to receptors governing potency, efficacy, bias and kinetics. This may help explain the actions of abused substances, advance fundamental receptor activation studies and design better medicines.

Background and PurposeThe dopamine D2 receptor is expressed as a short (D2S) and a long (D2L) isoform with 29 additional amino acids in the third intracellular loop. The D2S isoform shows higher presynaptic expression than the D2L isoform, and decreased D2S expression has recently been linked to an increased risk for schizophrenia. Here, we present the first investigation, at receptor isoform level, of kinetic differences in the G protein activation profiles of the D2S, compared with the D2L isoform.Experimental ApproachWe employed a NanoBRET‐based approach to G protein dissociation to interrogate the time‐resolved coupling profile of 3×HA‐tagged D2L and D2S to Gαi/o/z proteins in vitro.Key ResultsUsing dopamine as a D2 receptor agonist, we observed a more pronounced activation of Gαo and Gαz than Gαi proteins by D2L compared with D2S. This differentiation was not observed for D2S, which activated Gαo and Gαz with lower efficacy than D2L. These signalling differences were preserved on second messenger level and were not due to differences in receptor expression. Expanding to a set of seven full and partial D2 receptor agonists showed these effects were not restricted to dopamine but rather a mutual, receptor‐associated property. Contrasting this trend, we found that D2S activated G proteins faster than D2L upon full receptor activation.Conclusion and ImplicationsThe findings highlight that both D2L and D2S are mechanistically able to activate all non‐visual Gαi/o proteins. Thereby, they add to previous reports about isoform‐specificity to certain Gαi/o proteins observed in specific cell types.

G proteins are the major signal proteins of ∼800 receptors for medicines, hormones, neurotransmitters, tastants and odorants. GproteinDb offers integrated genomic, structural, and pharmacological data and tools for analysis, visualization and experiment design. Here, we present the first major update of GproteinDb greatly expanding its coupling data and structural templates, adding AlphaFold2 structure models of GPCR-G protein complexes and advancing the interactive analysis tools for their interfaces underlying coupling selectivity. We present insights on coupling agreement across datasets and parameters, including constitutive activity, agonist-induced activity and kinetics. GproteinDb is accessible at https://gproteindb.org.

Pharmacogenomics, the study of how an individual's genetic makeup influences their response to medications, is a rapidly evolving field with significant implications for personalized medicine. As researchers and healthcare professionals face challenges in exploring the intricate relationships between genetic profiles and therapeutic outcomes, the demand for effective and user-friendly tools to access and analyze genetic data related to drug responses continues to grow. To address these challenges, we have developed PGxDB, an interactive, web-based platform specifically designed for comprehensive pharmacogenomics research. PGxDB enables the analysis across a wide range of genetic and drug response data types - informing cell-based validations and translational treatment strategies. We developed a pipeline that uniquely combines the relationship between medications indexed with Anatomical Therapeutic Chemical (ATC) codes with molecular target profiles with their genetic variability and predicted variant effects. This enables scientists from diverse backgrounds - including molecular scientists and clinicians - to link genetic variability to curated drug response variability and investigate indication or treatment associations in a single resource. With PGxDB, we aim to catalyze innovations in pharmacogenomics research, empower drug discovery, support clinical decision-making, and pave the way for more effective treatment regimens. PGxDB is a freely accessible database available at https://pgx-db.org/.

G protein-coupled receptors (GPCRs) are membrane-spanning transducers mediating the actions of numerous physiological ligands and drugs. The GPCR database GPCRdb supports a large global research community with reference data, analysis, visualization, experiment design and dissemination. Here, we describe our sixth major GPCRdb release starting with an overview of all resources for receptors and ligands. As a major addition, all similar to 400 human odorant receptors and their orthologs in major model organisms can now be studied across the various data and tool resources. For the first time, a Data mapper page enables users to map their own data onto receptors visualized as a GPCRome wheel, tree, clusters, list or heatmap. The structure model data have been expanded with models of physiological ligand complexes and updated with new state-specific structure models of all human GPCRs (built using AlphaFold, RoseTTAFold and AlphaFold-Multistate). Furthermore, a structure or model (pdb file) can now be queried against GPCRdb's entire structure / model collection through a Structuresimilarity search page implementing FoldSeek. Finally, for ligands, new search tools can query names, database identifiers, similarities or substructures against integrated entries from the ChEMBL, Guide to Pharmacology, PDSP Ki, PubChem, DrugCentral and DrugBank databases. [Graphics]

G protein-coupled receptors (GPCRs) are physiologically abundant signaling hubs routing hundreds of extracellular signal substances and drugs into intracellular pathways. The GPCR database, GPCRdb supports > 5000 interdisciplinary researchers every month with reference data, analysis, visualization, experiment design and dissemination. Here, we present our fifth major GPCRdb release setting out with an overview of the many resources for receptor sequences, structures, and ligands. This includes recently published additions of class D generic residue numbers, a comparative structure analysis tool to identify functional determinants, trees clustering GPCR structures by 3D conformation, and mutations stabilizing inactive/active states. We provide new state-specific structure models of all human non-olfactory GPCRs built using AlphaFold2-MultiState. We also provide a new resource of endogenous ligands along with a larger number of surrogate ligands with bioactivity, vendor, and physiochemical descriptor data. The one-stop-shop ligand resources integrate ligands/data from the ChEMBL, Guide to Pharmacology, PDSP Ki and PubChem database. The GPCRdb is available athttps://gpcrdb.org.

Biased signaling gives hormones, probes or drugs distinct functional outcomes via the same receptor. The Biased Signaling Atlas ( https://BiasedSignalingAtlas.org ) provides a community hub with data and tools to advance this paradigm, which may yield safer and more potent drugs.

The 57-mer full-length GPR15L(25-81) peptide has been identified as the principal endogenous agonist of the G protein-coupled receptor GPR15. Its main activity resides in the C-terminal 11-mer GPR15L(71-81), which has full efficacy but ~40-fold lower potency than the full-length peptide. Here, we systematically investigated the structure-activity relationship of GPR15L(71-81) by truncations/extensions, alanine-scanning, and N- and C-terminal capping. The synthesized peptide analogues were tested at GPR15 stably expressed in HEK293A cells using a homogenous time-resolved Förster resonance energy transfer-based Gi cAMP functional assay. We show that the C-terminal α carboxyl group and the residues Leu78 , Pro75 , Val74 , and Trp72 are critical for receptor interaction and contribute significantly to the peptide potency. Furthermore, we tested the ability of GPR15L(71-81), C-terminally amidated GPR15L(71-81), and GPR15L(25-81) to activate the three GPR15 receptor mutants in a bioluminescence resonance energy transfer-based G protein activation assay. The results demonstrate that the Lys192 and Glu272 residues in GPR15 are important for the potency of the GPR15L peptide. Overall, our study identifies critical residues in the peptide and receptor sequences for future drug design.

The class Frizzled of G protein-coupled receptors (GPCRs), consisting of ten Frizzled (FZD 1-10 ) paralogs and Smoothened, remains one of the most enigmatic GPCR families. This class mediates signaling predominantly through Disheveled (DVL) or heterotrimeric G proteins. However, the mechanisms underlying pathway selection are elusive. Here we employ a structure-driven mutagenesis approach in combination with an extensive panel of functional signaling readouts to investigate the importance of conserved state-stabilizing residues in FZD 5 for signal specification. Similar data were obtained for FZD 4 and FZD 10 suggesting that our findings can be extrapolated to other members of the FZD family. Comparative molecular dynamics simulations of wild type and selected FZD 5 mutants further support the concept that distinct conformational changes in FZDs specify the signal outcome. In conclusion, we find that FZD 5 and FZDs in general prefer coupling to DVL rather than heterotrimeric G proteins and that distinct active state micro-switches in the receptor are essential for pathway selection arguing for conformational changes in the receptor protein defining transducer selectivity.

Serotonergic psychedelics are described to have activation of the serotonin 2A receptor (5-HT2A) as their main pharmacological action. Despite their relevance, the molecular mechanisms underlying the psychedelic effects induced by certain 5-HT2A agonists remain elusive. One of the proposed hypotheses is the occurrence of biased agonism, defined as the preferential activation of certain signaling pathways over others. This study comparatively monitored the efficiency of a diverse panel of 4-position-substituted (and N-benzyl-derived) phenylalkylamines to induce recruitment of β-arrestin2 (βarr2) or miniGαq to the 5-HT2A, allowing us to assess structure-activity relationships and biased agonism. All test compounds exhibited agonist properties with a relatively large range of both EC50 and Emax values. Interestingly, the lipophilicity of the 2C-X phenethylamines was correlated with their efficacy in both assays but yielded a stronger correlation in the miniGαq- than in the βarr2-assay. Molecular docking suggested that accommodation of the 4-substituent of the 2C-X analogues in a hydrophobic pocket between transmembrane helices 4 and 5 of 5-HT2A may contribute to this differential effect. Aside from previously used standard conditions (lysergic acid diethylamide (LSD) as a reference agonist and a 2 h activation profile to assess a compound's activity), serotonin was included as a second reference agonist, and the compounds' activities were also assessed using the first 30 min of the activation profile. Under all assessed circumstances, the qualitative structure-activity relationships remained unchanged. Furthermore, the use of two reference agonists allowed for the estimation of both "benchmark bias" (relative to LSD) and "physiology bias" (relative to serotonin).

Serotonin is a neurotransmitter regulating numerous physiological processes also modulated by drugs, for example, schizophrenia, depression, migraine, and obesity. However, these drugs typically have adverse effects caused by promiscuous binding across 12 serotonin and more than 20 homologous receptors. Recently, structures of the entire serotonin receptor family uncovered molecular ligand recognition. Here, we present a map of 19 'selectivity hotspots', that is, nonconserved binding site residues governing selectivity via favorable target interactions or repulsive 'off-target' contacts. Furthermore, we review functional rationale from observed ligand-binding affinities and mutagenesis effects. Unifying knowledge underlying specific probes and drugs is critical toward the functional characterization of different receptors and alleviation of adverse effects.

The orphan G protein-coupled receptor GPR139 is predominantly expressed in the central nervous system and has attracted considerable interest as a therapeutic target. However, the biological role of this receptor remains somewhat elusive, in part due to the lack of quality pharmacological tools to investigate GPR139 function. In an effort to understand GPR139 signaling and to identify improved compounds, in this study we performed virtual screening and analog searches, in combination with multiple pharmacological assays. We characterized GPR139-dependent signaling using previously published reference agonists in Ca2+ mobilization and inositol monophosphate accumulation assays, as well as a novel real-time GPR139 internalization assay. For the four reference agonists tested, the rank order of potency was conserved across signaling and internalization assays: JNJ-63533054 > Compound 1a » Takeda > AC4 > DL43, consistent with previously reported values. We noted an increased efficacy of JNJ-63533054-mediated inositol monophosphate signaling and internalization, relative to Compound 1a. We then performed virtual screening for GPR139 agonist and antagonist compounds that were screened and validated in GPR139 functional assays. We identified four GPR139 agonists that were active in all assays, with similar or reduced potency relative to known compounds. Likewise, compound analogs selected based on GPR139 agonist and antagonist substructure searches behaved similarly to their parent compounds. Thus, we have characterized GPR139 signaling for multiple new ligands using G protein-dependent assays and a new real-time internalization assay. These data add to the GPR139 tool compound repertoire, which could be optimized in future medical chemistry campaigns.