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Zhang H, Wu T, Wu Y, Peng Y, Wei X, Lu T, Jiao Y. Binding sites and design strategies for small molecule GLP-1R agonists. Eur J Med Chem 2024; 275:116632. [PMID: 38959726 DOI: 10.1016/j.ejmech.2024.116632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 06/23/2024] [Accepted: 06/24/2024] [Indexed: 07/05/2024]
Abstract
Glucagon-like peptide-1 receptor (GLP-1R) is a pivotal receptor involved in blood glucose regulation and influencing feeding behavior. It has received significant attention in the treatment of obesity and diabetes due to its potent incretin effect. Peptide GLP-1 receptor agonists (GLP-1RAs) have achieved tremendous success in the market, driving the vigorous development of small molecule GLP-1RAs. Currently, several small molecules have entered the clinical research stage. Additionally, recent discoveries of GLP-1R positive allosteric modulators (PAMs) are also unveiling new regulatory patterns and treatment methods. This article reviews the structure and functional mechanisms of GLP-1R, recent reports on small molecule GLP-1RAs and PAMs, as well as the optimization process. Furthermore, it combines computer simulations to analyze structure-activity relationships (SAR) studies, providing a foundation for exploring new strategies for designing small molecule GLP-1RAs.
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Affiliation(s)
- Haibo Zhang
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing, 211198, China
| | - Tianxiao Wu
- Jiangsu Vcare PharmaTech Co., Ltd., 136 Huakang Road, Nanjing, 211800, China
| | - Yong Wu
- Jiangsu Vcare PharmaTech Co., Ltd., 136 Huakang Road, Nanjing, 211800, China
| | - Yuran Peng
- Jiangsu Vcare PharmaTech Co., Ltd., 136 Huakang Road, Nanjing, 211800, China
| | - Xian Wei
- Department of Pharmacy, Youjiang Medical University for Nationalities, 98 ChengXiang Road, Baise, 533000, China.
| | - Tao Lu
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing, 211198, China.
| | - Yu Jiao
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing, 211198, China.
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2
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Zhang M, Chen T, Lu X, Lan X, Chen Z, Lu S. G protein-coupled receptors (GPCRs): advances in structures, mechanisms, and drug discovery. Signal Transduct Target Ther 2024; 9:88. [PMID: 38594257 PMCID: PMC11004190 DOI: 10.1038/s41392-024-01803-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 02/19/2024] [Accepted: 03/13/2024] [Indexed: 04/11/2024] Open
Abstract
G protein-coupled receptors (GPCRs), the largest family of human membrane proteins and an important class of drug targets, play a role in maintaining numerous physiological processes. Agonist or antagonist, orthosteric effects or allosteric effects, and biased signaling or balanced signaling, characterize the complexity of GPCR dynamic features. In this study, we first review the structural advancements, activation mechanisms, and functional diversity of GPCRs. We then focus on GPCR drug discovery by revealing the detailed drug-target interactions and the underlying mechanisms of orthosteric drugs approved by the US Food and Drug Administration in the past five years. Particularly, an up-to-date analysis is performed on available GPCR structures complexed with synthetic small-molecule allosteric modulators to elucidate key receptor-ligand interactions and allosteric mechanisms. Finally, we highlight how the widespread GPCR-druggable allosteric sites can guide structure- or mechanism-based drug design and propose prospects of designing bitopic ligands for the future therapeutic potential of targeting this receptor family.
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Affiliation(s)
- Mingyang Zhang
- Key Laboratory of Protection, Development and Utilization of Medicinal Resources in Liupanshan Area, Ministry of Education, Peptide & Protein Drug Research Center, School of Pharmacy, Ningxia Medical University, Yinchuan, 750004, China
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Ting Chen
- Department of Cardiology, Changzheng Hospital, Affiliated to Naval Medical University, Shanghai, 200003, China
| | - Xun Lu
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xiaobing Lan
- Key Laboratory of Protection, Development and Utilization of Medicinal Resources in Liupanshan Area, Ministry of Education, Peptide & Protein Drug Research Center, School of Pharmacy, Ningxia Medical University, Yinchuan, 750004, China
| | - Ziqiang Chen
- Department of Orthopedics, Changhai Hospital, Affiliated to Naval Medical University, Shanghai, 200433, China.
| | - Shaoyong Lu
- Key Laboratory of Protection, Development and Utilization of Medicinal Resources in Liupanshan Area, Ministry of Education, Peptide & Protein Drug Research Center, School of Pharmacy, Ningxia Medical University, Yinchuan, 750004, China.
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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3
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Fuselier T, Mota de Sa P, Qadir MMF, Xu B, Allard C, Meyers MM, Tiano JP, Yang BS, Gelfanov V, Lindsey SH, Dimarchi RD, Mauvais-Jarvis F. Efficacy of glucagon-like peptide-1 and estrogen dual agonist in pancreatic islets protection and pre-clinical models of insulin-deficient diabetes. Cell Rep Med 2022; 3:100598. [PMID: 35492248 PMCID: PMC9043999 DOI: 10.1016/j.xcrm.2022.100598] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/18/2022] [Accepted: 03/15/2022] [Indexed: 02/06/2023]
Abstract
We study the efficacy of a glucagon-like peptide-1 (GLP-1) and estrogen dual agonist (GLP1-E2) in pancreatic islet protection. GLP1-E2 provides superior protection from insulin-deficient diabetes induced by multiple low-dose streptozotocin (MLD-STZ-diabetes) and by the Akita mutation in mice than a GLP-1 monoagonist. GLP1-E2 does not protect from MLD-STZ-diabetes in estrogen receptor-α (ERα)-deficient mice and fails to prevent diabetes in Akita mice following GLP-1 receptor (GLP-1R) antagonism, demonstrating the requirement of GLP-1R and ERα for GLP1-E2 antidiabetic actions. In the MIN6 β cell model, GLP1-E2 activates estrogen action following clathrin-dependent, GLP-1R-mediated internalization and lysosomal acidification. In cultured human islet, proteomic bioinformatic analysis reveals that GLP1-E2 amplifies the antiapoptotic pathways activated by monoagonists. However, in cultured mouse islets, GLP1-E2 provides antiapoptotic protection similar to monoagonists. Thus, GLP1-E2 promotes GLP-1 and E2 antiapoptotic signals in cultured islets, but in vivo, additional GLP1-E2 actions in non-islet cells expressing GLP-1R are instrumental to prevent diabetes.
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Affiliation(s)
- Taylor Fuselier
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | - Paula Mota de Sa
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Healthcare System Medical Center, New Orleans, LA 70119, USA
| | - M M Fahd Qadir
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Healthcare System Medical Center, New Orleans, LA 70119, USA
| | - Beibei Xu
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | - Camille Allard
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | - Mathew M Meyers
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Joseph P Tiano
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Bin S Yang
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN 46241, USA
| | - Vasily Gelfanov
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN 46241, USA
| | - Sarah H Lindsey
- Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | | | - Franck Mauvais-Jarvis
- Deming Department of Medicine, Section of Endocrinology and Metabolism, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Healthcare System Medical Center, New Orleans, LA 70119, USA.
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4
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A review of glucoregulatory hormones potentially applicable to the treatment of Alzheimer’s disease: mechanism and brain delivery. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2022. [DOI: 10.1007/s40005-022-00566-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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5
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Zhang W, Zhang F, Hu Q, Xiao X, Ou L, Chen Y, Luo S, Cheng Y, Jiang Y, Ma X, Zhao Y. The emerging possibility of the use of geniposide in the treatment of cerebral diseases: a review. Chin Med 2021; 16:86. [PMID: 34454545 PMCID: PMC8400848 DOI: 10.1186/s13020-021-00486-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 08/01/2021] [Indexed: 12/19/2022] Open
Abstract
With the advanced discoveries in the field of pathogenesis, a series of cerebral diseases, such as cerebral ischaemia, Alzheimer's disease, and depression, have been found to have multiple signalling targets in the microenvironment. Only a few existing agents have been shown to have curative effects due to this specific circumstance. In recent decades, active ingredients isolated from natural plants have been shown to be crucial for original drug development. Geniposide, mainly extracted from Gardenia jasminoides Ellis, is representative of these natural products. Geniposide demonstrates various biological activities in the treatment of cerebral, cardiovascular, hepatic, tumorous, and other diseases. The multiple protective effects of geniposide on the brain have especially drawn increasing attention. Thus, this article specifically reviews the characteristics of current models of cerebral ischaemia and illustrates the possible effects of geniposide and its pathogenetic mechanisms on these models. Geniposide has been shown to significantly reduce the area of cerebral infarction and alleviate neuronal damage and necrosis mainly by inhibiting inflammatory signals, including NLRP3, TNF-α, IL-6, and IL-1β. Neuronal protection was also involved in activating the PI3K/Akt and Wnt/catenin pathways. Geniposide was able to increase autophagy and inhibit apoptosis by regulating the function of mTOR in treating Alzheimer's disease. Geniposide has also been shown to act as a glucagon-like peptide-1 receptor (GLP-1R) agonist to reduce amyloid plaques and inhibit oxidative stress to alleviate memory impairment as well as synaptic loss. Moreover, geniposide has been shown to exert antidepressant effects primarily by regulating the hypothalamic-pituitary-adrenal (HPA) axis. Detailed explorations have shown that the biological activities of inhibiting inflammatory cytokine secretion, alleviating oxidative stress, and suppressing mitochondrial damage are also involved in the mechanism of action of geniposide. Therefore, geniposide is a promising agent awaiting further exploration for the treatment of cerebral diseases via various phenotypes or signalling pathways.
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Affiliation(s)
- Wenwen Zhang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Fangling Zhang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Qichao Hu
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Xiaolin Xiao
- Hospital of Chengdu University of Traditional Chinese Medicine, School of Clinical Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Linbo Ou
- College of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Yuan Chen
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Shiqing Luo
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Yonghong Cheng
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Yinxiao Jiang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China
| | - Xiao Ma
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China.
| | - Yanling Zhao
- Department of Pharmacy, The Fifth Medical Centre of PLA General Hospital, Beijing, 100039, China.
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6
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Cong Z, Chen LN, Ma H, Zhou Q, Zou X, Ye C, Dai A, Liu Q, Huang W, Sun X, Wang X, Xu P, Zhao L, Xia T, Zhong W, Yang D, Eric Xu H, Zhang Y, Wang MW. Molecular insights into ago-allosteric modulation of the human glucagon-like peptide-1 receptor. Nat Commun 2021; 12:3763. [PMID: 34145245 PMCID: PMC8213797 DOI: 10.1038/s41467-021-24058-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/28/2021] [Indexed: 01/04/2023] Open
Abstract
The glucagon-like peptide-1 (GLP-1) receptor is a validated drug target for metabolic disorders. Ago-allosteric modulators are capable of acting both as agonists on their own and as efficacy enhancers of orthosteric ligands. However, the molecular details of ago-allosterism remain elusive. Here, we report three cryo-electron microscopy structures of GLP-1R bound to (i) compound 2 (an ago-allosteric modulator); (ii) compound 2 and GLP-1; and (iii) compound 2 and LY3502970 (a small molecule agonist), all in complex with heterotrimeric Gs. The structures reveal that compound 2 is covalently bonded to C347 at the cytoplasmic end of TM6 and triggers its outward movement in cooperation with the ECD whose N terminus penetrates into the GLP-1 binding site. This allows compound 2 to execute positive allosteric modulation through enhancement of both agonist binding and G protein coupling. Our findings offer insights into the structural basis of ago-allosterism at GLP-1R and may aid the design of better therapeutics. The glucagon-like peptide-1 (GLP-1) receptor is a key regulator of glucose homeostasis and a drug target for type 2 diabetes but available GLP-1R agonists are suboptimal due to several side-effects. Here authors report the cryo-EM structure of GLP-1R bound to an ago-allosteric modulator in complex with heterotrimeric Gs which offers insights into the molecular details of ago-allosterism.
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Affiliation(s)
- Zhaotong Cong
- School of Pharmacy, Fudan University, Shanghai, China.,The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Li-Nan Chen
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Honglei Ma
- The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Qingtong Zhou
- School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xinyu Zou
- School of Artificial Intelligence and Automation, Huazhong University of Science and Technology, Wuhan, China
| | - Chenyu Ye
- School of Pharmacy, Fudan University, Shanghai, China.,The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Antao Dai
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Qing Liu
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Wei Huang
- Qilu Regor Therapeutics, Inc., Shanghai, China
| | | | - Xi Wang
- The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Peiyu Xu
- The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Lihua Zhao
- The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Tian Xia
- School of Artificial Intelligence and Automation, Huazhong University of Science and Technology, Wuhan, China
| | - Wenge Zhong
- Qilu Regor Therapeutics, Inc., Shanghai, China
| | - Dehua Yang
- The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,University of Chinese Academy of Sciences, Beijing, China.
| | - H Eric Xu
- The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,University of Chinese Academy of Sciences, Beijing, China.
| | - Yan Zhang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China. .,MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Medicine, Hangzhou, China. .,Key Laboratory of Immunity and Inflammatory Diseases of Zhejiang Province, Hangzhou, China. .,Zhejiang Laboratory for Systems and Precision Medicine, Zhejiang University Medical Center, Hangzhou, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
| | - Ming-Wei Wang
- School of Pharmacy, Fudan University, Shanghai, China. .,The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,School of Basic Medical Sciences, Fudan University, Shanghai, China. .,The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. .,University of Chinese Academy of Sciences, Beijing, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
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7
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Discovery of small molecule positive allosteric modulators of the secretin receptor. Biochem Pharmacol 2021; 185:114451. [PMID: 33545115 DOI: 10.1016/j.bcp.2021.114451] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/25/2021] [Accepted: 01/25/2021] [Indexed: 12/12/2022]
Abstract
The secretin receptor (SCTR) is a prototypic Class B1 G protein-coupled receptor (GPCR) that represents a key target for the development of therapeutics for the treatment of cardiovascular, gastrointestinal, and metabolic disorders. However, no non-peptidic molecules targeting this receptor have yet been disclosed. Using a high-throughput screening campaign directed at SCTR to identify small molecule modulators, we have identified three structurally related scaffolds positively modulating SCTRs. Here we outline a comprehensive study comprising a structure-activity series based on commercially available analogs of the three hit scaffold sets A (2-sulfonyl pyrimidines), B (2-mercapto pyrimidines) and C (2-amino pyrimidines), which revealed determinants of activity, cooperativity and specificity. Structural optimization of original hits resulted in analog B2, which substantially enhances signaling of truncated secretin peptides and prolongs residence time of labeled secretin up to 13-fold in a dose-dependent manner. Furthermore, we found that investigated compounds display structural similarity to positive allosteric modulators (PAMs) active at the glucagon-like peptide-1 receptor (GLP-1R), and we were able to confirm cross-recognition of that receptor by a subset of analogs. Studies using SCTR and GLP-1R mutants revealed that scaffold A, but not B and C, likely acts via two distinct mechanisms, one of which constitutes covalent modification of Cys-347GLP-1R known from GLP-1R-selective modulators. The scaffolds identified in this study might not only serve as novel pharmacologic tools to decipher SCTR- or GLP-1R-specific signaling pathways, but also as structural leads to elucidate allosteric binding sites facilitating the future development of orally available therapeutic approaches targeting these receptors.
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Vizurraga A, Adhikari R, Yeung J, Yu M, Tall GG. Mechanisms of adhesion G protein-coupled receptor activation. J Biol Chem 2020; 295:14065-14083. [PMID: 32763969 DOI: 10.1074/jbc.rev120.007423] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/31/2020] [Indexed: 12/19/2022] Open
Abstract
Adhesion G protein-coupled receptors (AGPCRs) are a thirty-three-member subfamily of Class B GPCRs that control a wide array of physiological processes and are implicated in disease. AGPCRs uniquely contain large, self-proteolyzing extracellular regions that range from hundreds to thousands of residues in length. AGPCR autoproteolysis occurs within the extracellular GPCR autoproteolysis-inducing (GAIN) domain that is proximal to the N terminus of the G protein-coupling seven-transmembrane-spanning bundle. GAIN domain-mediated self-cleavage is constitutive and produces two-fragment holoreceptors that remain bound at the cell surface. It has been of recent interest to understand how AGPCRs are activated in relation to their two-fragment topologies. Dissociation of the AGPCR fragments stimulates G protein signaling through the action of the tethered-peptide agonist stalk that is occluded within the GAIN domain in the holoreceptor form. AGPCRs can also signal independently of fragment dissociation, and a few receptors possess GAIN domains incapable of self-proteolysis. This has resulted in complex theories as to how these receptors are activated in vivo, complicating pharmacological advances. Currently, there is no existing structure of an activated AGPCR to support any of the theories. Further confounding AGPCR research is that many of the receptors remain orphans and lack identified activating ligands. In this review, we provide a detailed layout of the current theorized modes of AGPCR activation with discussion of potential parallels to mechanisms used by other GPCR classes. We provide a classification means for the ligands that have been identified and discuss how these ligands may activate AGPCRs in physiological contexts.
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Affiliation(s)
- Alexander Vizurraga
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
| | - Rashmi Adhikari
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
| | - Jennifer Yeung
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
| | - Maiya Yu
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
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