Identical complementary deoxyribonucleic acids encode a human renal and bone parathyroid hormone (PTH)/PTH-related peptide receptor.
Identical complementary DNAs (cDNAs) that encode a 593-amino acid human PTH (PTH)/PTH-related peptide (PTHrP) receptor were isolated by hybridization techniques from two cDNA libraries which had been constructed from human kidney and human osteoblast-like osteosarcoma cells (SaOS-2). Northern blot analysis of total RNA from human bone- and kidney-derived tissue revealed one single major messenger RNA species of about 2.5 kilobases in both tissues. The human PTH/PTHrP receptor has 91% and 81% identity, respectively, with the previously cloned rat and opossum receptors, indicating a high degree of conservation among mammals. Despite this striking degree of amino-acid conservation, the human PTH/PTHrP receptor has several unique biological properties when transiently expressed in COS-7 cells. The apparent dissociation constants for [Nle8,18,Tyr34] bovine PTH(1-34) amide [bPTH(1-34)] are similar for the human and the rat receptor (approximately 8 vs. approximately 15 nM) whereas [Tyr36]PTHrP(1-36) amide has a slightly lower affinity for the human (15-40 nM) than for the rat receptor (approximately 15 nM). Both ligands stimulate efficiently and with similar efficacy the accumulation of intracellular cAMP. The affinities for the antagonists [Nle8,18,Tyr34] bPTH(3.34) amide [bPTH(3-34)] and in particular for [Nle8,18,Tyr34] bPTH(7-34) amide [bPTH(7-34)] are considerably higher for the human receptor, e.g. approximately 8 nM vs. 30 nM for bPTH(3-34) and approximately 100 nM vs. 5000 nM for bPTH(7-34), respectively. Similar biological findings were previously attributed to differences in species- and/or organ-specific PTH/PTHrP receptors. The expression of the recombinant, highly homologous rat and human receptors in a uniform environment indicate that the moderate differences in the primary receptor structure have profound consequences for the receptor binding affinity of amino-terminally truncated PTH analogs. Furthermore, the molecular cloning of identical cDNAs encoding a human PTH/PTHrP receptor from the two major target organs for PTH, bone and kidney, provides strong evidence for one single PTH/PTHrP receptor in both organs, although additional and/or alternatively spliced receptors cannot be excluded.
Schipani
E
E
Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Karga
H
H
Karaplis
A C
AC
Potts
J T
JT
Kronenberg
H M
HM
Segre
G V
GV
Abou-Samra
A B
AB
Jüppner
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001842:Bone and Bones / Q000737:chemistry*; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification*; D006031:Glycosylation; D007668:Kidney / Q000737:chemistry*; D008969:Molecular Sequence Data; D012516:Osteosarcoma; D016133:Polymerase Chain Reaction; D051381:Rats; D044168:Receptor, Parathyroid Hormone, Type 1; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics*; D018016:Receptors, Parathyroid Hormone; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
D044168:Receptor, Parathyroid Hormone, Type 1; D011956:Receptors, Cell Surface; D018016:Receptors, Parathyroid Hormone; D004247:DNA