New insights into interactions between the human PTH/PTHrP receptor and agonist/antagonist binding.
We prepared a polyclonal antiserum [Ab-(88-97)] against residues 8-97 of the NH2-terminal tail of the human (h) parathyroid hormone (PTH)/PTH-related protein (PTHrP) receptor. Ab-(88-97) bound specifically to the receptor, as assessed by fluorescence-activated cell sorter analysis of HEK C21 cells, which stably express approximately 400,000 hPTH/PTHrP receptors per cell. Unlike PTH, Ab-(88-97) binding did not elicit either adenosine 3',5'-cyclic monophosphate or intracellular calcium concentration signaling responses in these cells. Incubation of C21 cells for 90 min at 4 degrees C with hPTH-(1-34) plus antiserum reduced the Ab-(88-97) binding to the cells by up to 40-50% of control values in a PTH concentration-dependent fashion with a half-maximal effective concentration of approximately 5 nM. The decrease in Ab-(88-97) binding caused by hPTH-(1-34) was completely reversed by coincubation 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.
Fukayama
S
S
Department of Molecular and Cellular Toxicology, Harvard School of Public Health, Boston, MA, USA.
Royo
M
M
Sugita
M
M
Imrich
A
A
Chorev
M
M
Suva
L J
LJ
Rosenblatt
M
M
Tashjian
A H
AH
D000818:Animals; D002460:Cell Line; D018604:Epitope Mapping; D006041:Goats; D006801:Humans; D007106:Immune Sera; D010281:Parathyroid Hormone / Q000276:immunology / Q000378:metabolism; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding; D044168:Receptor, Parathyroid Hormone, Type 1; D018016:Receptors, Parathyroid Hormone / Q000276:immunology / Q000378:metabolism*; D019379:Teriparatide / Q000031:analogs & derivatives / Q000276:immunology / Q000378:metabolism
D007106:Immune Sera; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D044168:Receptor, Parathyroid Hormone, Type 1; D018016:Receptors, Parathyroid Hormone; D019379:Teriparatide; C031617:parathyroid hormone (3-34); C035748:parathyroid hormone (1-34)amide