{"doi":"10.1021/acs.biochem.4c00779","title":"G Protein Selectivity in Dopamine Receptors is Determined before GDP Release","abstract":"High Resolution Image Download MS PowerPoint Slide Dopaminergic signaling in neurophysiological processes utilizes multiple G proteins. The dopamine receptor subtypes D1R/D5R selectively couple to G s/olf proteins, while D2R/D3R/D4R is selective for G i/o proteins. The molecular mechanisms underlying this selectivity are not clear, so structural models of D1R and D2R were built in complex with their cognate and noncognate G proteins, in either GDP-bound or nucleotide-free states. These eight complexes were relaxed in a membrane environment through 2 μs-long molecular dynamics (MD) simulations. A thermodynamic analysis of these complexes provided free energies of G protein binding to the receptors that was consistent with D1R’s preference for G s protein and D2R’s preference for G i protein, but only for the GDP-bound states of the G proteins, suggesting that G s vs G i selectivity happens before GDP release. Biophysical measurements of receptor preassociation with G proteins in cells were also consistent with these preferences. The role of the Gα protein’s α5-helix in G protein selectivity was probed by switching the last 18 residues of Gα between Gα s and Gα i to create chimeric G i18s and G s18i proteins. Thermodynamic analysis of MD-relaxed chimeric complexes revealed a complete switch in G protein binding selectivity for both D1R and D2R receptors, but again only for the GDP-bound G proteins. Biophysical measurements of receptor preassociation with G proteins in cells also overall supported this selectivity alteration. These studies have shown that G protein selectivity for dopamine receptors is conferred before GDP release; however, additional molecular events may be needed for a productive coupling to enable a successful GDP/GTP exchange.","journal":"Biochemistry","year":2025,"id":565799,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9503,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1227432,"name":"Ari S. Hilibrand","orcid":"0000-0003-4169-0880","position":1,"is_corresponding":false},{"id":732425,"name":"Jeffrey S. Smith","orcid":"0000-0003-2840-2899","position":2,"is_corresponding":false},{"id":699923,"name":"Jennifer Portillo","orcid":null,"position":3,"is_corresponding":false},{"id":239851,"name":"Andrew C. Kruse","orcid":"0000-0002-1467-1222","position":4,"is_corresponding":false},{"id":433590,"name":"Ravinder Abrol","orcid":"0000-0001-7333-6793","position":5,"is_corresponding":false},{"id":1295829,"name":"Caesar Tawfeeq","orcid":null,"position":0,"is_corresponding":true}],"reference_count":70,"raw_metadata":null,"created_at":"2026-07-19T02:56:32.546082Z","pmid":"40358213","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}