New insights into interactions between the human pth/pthrp receptor
and agonist/antagonist binding.
Fukayama, Shoichi, Miryam Royo, Masahiko Sugita, Amy Imrich, Michael
Chorev, Larry J. Suva, Michael Rosenblatt, and Armen H. Tashjian.
Department of Molecular and Cellular Toxicology (S.F. and A.H.T.);
Program in Physiology, Department of Environmental Health (A.I.),
Harvard School of Public Health, Department of Biological Chemistry
and Molecular Pharmacology, Harvard Medical School (A.H.T.);
Lymphocyte Biology Section, Division of Rheumatology and Immunology,
Brigham and Women_s Hospital, Harvard Medical School (M.S.), and
Division of Bone and Mineral Metabolism, Harvard-Thorndike and
Charles A. Dana Laboratories, Department of Medicine, Beth Israel
Deaconess Medical Center, Harvard Medical School (M.R., M.C., L.J.S.,
and M.R.), Boston, MA 02115
APStracts 4:0253E, 1997.
We have prepared a polyclonal antiserum [Ab(88-97)] against residues
88-97 of the N-terminal tail of the human (h) PTH/PTHrP receptor.
Ab(88-97) bound specifically to the receptor, as assessed by FACS
(fluorescence-activated cell sorter) analysis of HEK C21 cells which
stably express 400,000 hPTH/PTHrP- receptors/cell. Unlike PTH, Ab(88
-97) binding did not elicit either cAMP or [Ca2+]i signaling responses
in these cells. Incubation of C21 cells for 90 min at 4oC with
hPTH(1-34) plus antiserum reduced the Ab(88-97) binding to the cells,
by up to 40-50% of control values, to the cells in a PTH
concentration-dependent fashion with an EC50 of about 5 nM. The
decrease in Ab(88-97) binding caused by hPTH(1-34) was completely
reversed by co-incubation with hPTHrP(7-34). We conclude that
residues 88-97 of the hPTH/PTHrPR are involved, either directly or
indirectly, in agonist but not antagonist binding to the receptor.
Received 4 September 1997; accepted in final form 10 November
1997.
APS Manuscript Number E419-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 12 December 1997