Determinants of [Arg2]PTH-(1-34) binding and signaling in the transmembrane region of the parathyroid hormone receptor.
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.
Gardella
T J
TJ
Endocrine Unit, Massachusetts General Hospital, Boston.
Jüppner
H
H
Wilson
A K
AK
Keutmann
H T
HT
Abou-Samra
A B
AB
Segre
G V
GV
Bringhurst
F R
FR
Potts
J T
JT
Nussbaum
S R
SR
Kronenberg
H M
HM
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*
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D018016:Receptors, Parathyroid Hormone; D019379:Teriparatide; C089037:parathyroid hormone (1-34), Arg(2)-