{"doi":"10.1101/2021.07.15.452545","title":"Identification of G Protein α <sub>i</sub> Signaling Partners by Proximity Labeling Reveals a Network of Interactions that Includes PDZ-RhoGEF","abstract":"Abstract G protein-coupled receptors (GPCRs) that couple to the Gi family of G proteins are key regulators of cell and tissue physiology. Our recent work has discovered novel roles for Gα i in migration of neutrophils and fibrosarcoma cells downstream of activated chemoattractant receptors, but the molecular target(s) of Gα i in these processes remain to be identified. We adopted an intact cell proximity-based labeling approach using BioID2 coupled to tandem mass tag (TMT)-based quantitative proteomics to identify proteins that selectively interact with the GTP-bound form of Gα i1 . Multiple targets were identified and validated for selective biotinylation by active BioID2-Gα i1 (Q204L), suggesting a previously unappreciated network of interactions for activated Gα i proteins in intact cells. Extensive characterization of one candidate protein, PDZ-RhoGEF (PRG), revealed that active-Gα i1 strongly activates PRG. Strikingly, large differences in the ability of Gα i1 , Gα i2 , and Gα i3 isoforms to activate PRG were observed despite over 85% sequence identity. We also demonstrate the functional relevance of the interaction between active Gα i and PRG ex vivo in primary human neutrophils. Identification and characterization of new targets regulated by Gα i both individually and in networks provide insights that will aid not only in investigation of diverse functional roles of Gi-coupled GPCRs in biology but also in the development of novel therapeutic approaches. Summary Proximity-based labeling approach was used to identify signaling networks and signaling mechanisms downstream of Gi-coupled receptors.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2021,"id":217668,"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":3,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9535,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":493890,"name":"Saji Abraham","orcid":"0000-0001-7035-0610","position":1,"is_corresponding":false},{"id":638946,"name":"Shuvasree SenGupta","orcid":"0000-0002-1367-1685","position":2,"is_corresponding":false},{"id":226086,"name":"Carole A. Parent","orcid":"0000-0002-1518-1452","position":3,"is_corresponding":false},{"id":336936,"name":"Alan V. Smrcka","orcid":"0000-0003-3099-8812","position":4,"is_corresponding":false},{"id":504787,"name":"Naincy R. Chandan","orcid":"0000-0001-8097-1867","position":0,"is_corresponding":true}],"reference_count":58,"raw_metadata":null,"created_at":"2026-07-18T23:53:20.374789Z","pmid":null,"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":[]}