title: Determinants of [Arg2]PTH-(1-34) binding and signaling in the transmembrane region of the parathyroid hormone receptor.
abstract: Previously, we reported that [Arg2]PTH-(1-34) bound to the rat osteosarcoma cell line, ROS 17/2.8, with 2-fold higher apparent affinity than it did to the opossum kidney cell line, OK, yet the analog was only a weak partial agonist for cAMP stimulation with ROS 17/2.8 cells, whereas it was a full cAMP agonist with OK cells. These results suggested that the rat and opossum PTH receptors differ in a region recognized by the hormone's amino-terminus. In this report we show that the cloned PTH receptors derived from ROS 17/2.8 and OK cells, expressed in COS-7 cells, also displayed altered responses to [Arg2]PTH-(1-34). Thus, [Arg2]PTH-(1-34) bound to the cloned rat PTH receptor with 7-fold higher affinity than it did to the cloned opossum PTH receptor, and in cAMP stimulation assays, it was a much weaker agonist with the rat receptor than it was with the opossum receptor. Studies with rat/opossum PTH receptor chimeras suggested that the membrane-spanning region of the receptor contributed to the different binding and signaling responses to [Arg2]PTH-(1-34). Point mutation analysis identified three sites in or near the extracellular ends of transmembrane domains V and VI, which specifically affected [Arg2]PTH-(1-34) binding and signaling.
authors.affiliation: Endocrine Unit, Massachusetts General Hospital, Boston.
authors.forename: T J
authors.initials: TJ
authors.lastname: Gardella
authors.forename: H
authors.initials: H
authors.lastname: Jüppner
authors.forename: A K
authors.initials: AK
authors.lastname: Wilson
authors.forename: H T
authors.initials: HT
authors.lastname: Keutmann
authors.forename: A B
authors.initials: AB
authors.lastname: Abou-Samra
authors.forename: G V
authors.initials: GV
authors.lastname: Segre
authors.forename: F R
authors.initials: FR
authors.lastname: Bringhurst
authors.forename: J T
authors.initials: JT
authors.lastname: Potts
authors.forename: S R
authors.initials: SR
authors.lastname: Nussbaum
authors.forename: H M
authors.initials: HM
authors.lastname: Kronenberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002678:Chimera; D008969:Molecular Sequence Data; D009893:Opossums; D010281:Parathyroid Hormone / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D017354:Point Mutation; D051381:Rats; D018016:Receptors, Parathyroid Hormone / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D019379:Teriparatide / Q000031:analogs & derivatives*
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D018016:Receptors, Parathyroid Hormone; D019379:Teriparatide; C089037:parathyroid hormone (1-34), Arg(2)-