title: Orexin/hypocretin receptor chimaeras reveal structural features important for orexin peptide distinction.
abstract: We wanted to analyze the basis for the distinction between OX(1) and OX(2) orexin receptors by the known agonists, orexin-A, orexin-B and Ala(11), D-Leu(15)-orexin-B, of which the latter two show some selectivity for OX(2). For this, chimaeric OX(1)/OX(2) and OX(2)/OX(1) orexin receptors were generated. The receptors were transiently expressed in HEK-293 cells, and potencies of the agonists to elicit cytosolic Ca(2+) elevation were measured. The results show that the N-terminal regions of the receptor are most important, and the exchange of the area from the C-terminal part of the transmembrane helix 2 to the transmembrane helix 4 is enough to lead to an almost total change of the receptor's ligand profile.
authors.affiliation: Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Jaana
authors.initials: J
authors.lastname: Putula
authors.forename: Pauli M
authors.initials: PM
authors.lastname: Turunen
authors.forename: Lisa
authors.initials: L
authors.lastname: Johansson
authors.forename: Johnny
authors.initials: J
authors.lastname: Näsman
authors.forename: Runar
authors.initials: R
authors.lastname: Ra
authors.forename: Laura
authors.initials: L
authors.lastname: Korhonen
authors.forename: Jyrki P
authors.initials: JP
authors.lastname: Kukkonen
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009479:Neuropeptides / Q000737:chemistry / Q000494:pharmacology*; D064446:Orexin Receptors; D000068797:Orexins; D020033:Protein Isoforms / Q000819:agonists / Q000737:chemistry / Q000235:genetics; D017433:Protein Structure, Secondary; D043562:Receptors, G-Protein-Coupled / Q000819:agonists* / Q000737:chemistry / Q000235:genetics; D018013:Receptors, Neuropeptide / Q000819:agonists* / Q000737:chemistry / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000819:agonists* / Q000737:chemistry
chemical_list: C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D020033:Protein Isoforms; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D011993:Recombinant Fusion Proteins