title: Histidine(7.36(305)) in the conserved peptide receptor activation domain of the gonadotropin releasing hormone receptor couples peptide binding and receptor activation.
abstract: Transmembrane helix seven residues of G protein-coupled receptors (GPCRs) couple agonist binding to a conserved receptor activation mechanism. Amino-terminal residues of the GnRH peptide determine agonist activity. We investigated GnRH interactions with the His(7.36(305)) residue of the GnRH receptor, using functional and computational analysis of modified GnRH receptors and peptides. Non-polar His(7.36(305)) substitutions decreased receptor affinity for GnRH four- to forty-fold, whereas GnRH signaling potency was more decreased (~150-fold). Uncharged polar His(7.36(305)) substitutions decreased GnRH potency, but not affinity. [2-Nal(3)]-GnRH retained high affinity at receptors with non-polar His(7.36(305)) substitutions, supporting a role for His(7.36(305)) in recognizing Trp(3) of GnRH. Compared with GnRH, [2-Nal(3)]-GnRH potency was lower at the wild type GnRH receptor, but unchanged or higher at mutant receptors. Results suggest that His(7.36(305)) of the GnRH receptor forms two distinct interactions that determine binding to Trp(3) and couple agonist binding to the conserved transmembrane domain network that activates GPCRs.
authors.affiliation: Medical Research Council Receptor Biology Research Unit, Institute of Infectious Diseases and Molecular Medicine, Division of Medical Biochemistry, University of Cape Town Health Sciences Faculty, Observatory, Cape Town 7925, South Africa.
authors.forename: Nkateko M I
authors.initials: NM
authors.lastname: Mayevu
authors.affiliation: Department of Physiology and Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul 138-736, Korea.
authors.forename: Han
authors.initials: H
authors.lastname: Choe
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92039, USA.
authors.forename: Ruben
authors.initials: R
authors.lastname: Abagyan
authors.affiliation: Graduate School of Medicine, Korea University, Seoul 136-705, Korea.
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Seong
authors.affiliation: Medical Research Council Receptor Biology Research Unit, Institute of Infectious Diseases and Molecular Medicine, Division of Medical Biochemistry, University of Cape Town Health Sciences Faculty, Observatory, Cape Town 7925, South Africa; Mammal Research Institute, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Millar
authors.affiliation: Medical Research Council Receptor Biology Research Unit, Institute of Infectious Diseases and Molecular Medicine, Division of Medical Biochemistry, University of Cape Town Health Sciences Faculty, Observatory, Cape Town 7925, South Africa.
authors.forename: Arieh A
authors.initials: AA
authors.lastname: Katz
authors.affiliation: Medical Research Council Receptor Biology Research Unit, Institute of Infectious Diseases and Molecular Medicine, Division of Medical Biochemistry, University of Cape Town Health Sciences Faculty, Observatory, Cape Town 7925, South Africa; School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Private bag 3, Wits 2050, South Africa. Electronic address: colleen.flanagan@wits.ac.za.
authors.forename: Colleen A
authors.initials: CA
authors.lastname: Flanagan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D019556:COS Cells; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry / Q000502:physiology; D006639:Histidine / Q000378:metabolism*; D007295:Inositol Phosphates / Q000096:biosynthesis; D051379:Mice; D008958:Models, Molecular; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011966:Receptors, LHRH / Q000737:chemistry / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D007295:Inositol Phosphates; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D006639:Histidine
keywords: G protein-coupled receptor (GPCR); GnRH; Hormone receptor; Peptide hormone; Peptide interaction; Receptor structure-function