title: The key residue within the second extracellular loop of human EP3 involved in selectively turning down PGE2- and retaining PGE1-mediated signaling in live cells.
abstract: Key residues and binding mechanisms of PGE1and PGE2on prostanoid receptors are poorly understood due to the lack of X-ray structures for the receptors. We constructed a human EP3 (hEP3) model through integrative homology modeling using the X-ray structure of the β2-adrenergic receptor transmembrane domain and NMR structures of the thromboxane A2 receptor extracellular loops. PGE1and PGE2docking into the hEP3 model showed differing configurations within the extracellular ligand recognition site. While PGE2could form possible binding contact with S211, PGE1is unable to form similar contacts. Therefore, S211 could be the critical residue for PGE2recognition, but is not a significant for PGE1. This prediction was confirmed using HEK293 cells transfected with hEP3 S211L cDNA. The S211L cells lost PGE2binding and signaling. Interestingly, the S211L cells retained PGE1-mediated signaling. It indicates that S211 within the second extracellular loop is a key residue involved in turning down PGE2signaling. Our study provided information that S211L within EP3 is the key residue to distinguish PGE1and PGE2binding to mediate diverse biological functions at the initial recognition step. The S211L mutant could be used as a model for studying the binding mechanism and signaling pathway specifically mediated by PGE1.
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Hironari
authors.initials: H
authors.lastname: Akasaka
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Natasha
authors.initials: N
authors.lastname: Thaliachery
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Xianghai
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Marissa
authors.initials: M
authors.lastname: Blumenthal
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Nikhar
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Emma E
authors.initials: EE
authors.lastname: Murdoch
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Qinglan
authors.initials: Q
authors.lastname: Ling
authors.affiliation: Center for Experimental Therapeutics and Pharmacoinformatics and Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204-5037, USA.
authors.forename: Ke-He
authors.initials: KH
authors.lastname: Ruan
mesh_terms: D000527:Alprostadil / Q000737:chemistry*; D001665:Binding Sites; D020013:Calcium Signaling; D018360:Crystallography, X-Ray; D018076:DNA, Complementary / Q000737:chemistry; D015232:Dinoprostone / Q000737:chemistry*; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D000072417:Protein Domains; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry; D058308:Receptors, Prostaglandin E, EP3 Subtype / Q000737:chemistry* / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry; D015398:Signal Transduction
chemical_list: D018076:DNA, Complementary; D008024:Ligands; C545647:PTGER3 protein, human; D018343:Receptors, Adrenergic, beta-2; D058308:Receptors, Prostaglandin E, EP3 Subtype; D011994:Recombinant Proteins; D000527:Alprostadil; D015232:Dinoprostone
keywords: EP selectivity; G protein-coupled receptor (GPCR); Prostaglandin; Prostaglandin E1; Prostaglandin E2; Receptor regulation