title: Negative cooperativity in H2 relaxin binding to a dimeric relaxin family peptide receptor 1.
abstract: H2 relaxin, a member of the insulin superfamily, binds to the G-protein-coupled receptor RXFP1 (relaxin family peptide 1), a receptor that belongs to the leucine-rich repeat (LRR)-containing subgroup (LGRs) of class A GPCRs. We recently demonstrated negative cooperativity in INSL3 binding to RXFP2 and showed that this subgroup of GPCRs functions as constitutive dimers. In this work, we investigated whether the binding of H2 relaxin to RXFP1 also shows negative cooperativity, and whether this receptor functions as a dimer using BRET(2). Both binding and dissociation were temperature dependent, and the pH optimum for binding was pH 7.0. Our results showed that RXFP1 is a constitutive dimer with negative cooperativity in ligand binding, that dimerization occurs through the 7TM domain, and that the ectodomain has a stabilizing effect on this interaction. Dimerization and negative cooperativity appear to be general properties of LGRs involved in reproduction as well as other GPCRs.
authors: Receptor Systems Biology Laboratory, Hagedorn Research Institute, Gentofte, Denmark.
authors: Angela Manegold
authors: AM
authors: Svendsen
authors: Anna
authors: A
authors: Zalesko
authors: Julie
authors: J
authors: Kønig
authors: Milka
authors: M
authors: Vrecl
authors: Anders
authors: A
authors: Heding
authors: Jesper Bøggild
authors: JB
authors: Kristensen
authors: John D
authors: JD
authors: Wade
authors: Ross A D
authors: RA
authors: Bathgate
authors: Pierre
authors: P
authors: De Meyts
authors: Jane
authors: J
authors: Nøhr
mesh_terms: D001667:Binding, Competitive / Q000502:physiology*; D002478:Cells, Cultured; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D009994:Osmolar Concentration; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D055503:Protein Multimerization; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism* / Q000502:physiology; D018000:Receptors, Peptide / Q000378:metabolism* / Q000502:physiology; D012065:Relaxin / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics / Q000502:physiology; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D007457:Iodine Radioisotopes; C095068:RLN2 protein, human; C417543:RXFP1 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D012065:Relaxin