Comparison of parathyroid hormone receptors in rat osteosarcoma cells and kidney.
Parathyroid hormone/parathyroid-hormone-related peptide (PTH/PTHrP) receptors have been characterized with chicken parathyroid hormone related protein [Tyr36]chPTHrP(1-36)amide (chPTHrP(1-36)) as radioligand in rat UMR-106 osteosarcoma (UMR) cells and in rat renal cortical membranes (RCM). Binding of 125 pM [125I][Tyr36]chPTHrP(1-36) was displaced by chPTHrP(1-36) with ID50 values of 2.6 +/- 0.22 nM (mean +/- S.E.) and 0.9 +/- 0.03 nM in UMR cells and RCM, respectively. ID50 values in membranes from UMR cells and RCM were the same in the presence and absence of 10 microM guanosine-5'-O-(3-thiotriphosphate). Rat [Nle8,18] PTH(1-34) was 5-fold more potent than chPTHrP(1-36) in RCM, but not in UMR cells. Hill coefficients derived from binding inhibition were 0.93 and 0.35 in UMR and RCM, respectively. For affinity labeling, N-hydroxysuccinimidyl-4-azidobenzoate-modified [125I]chPTHrP(1-36) was used. Specifically-labeled PTH/PTHrP-binding proteins had a molecular mass of 83 kDa in UMR cells and RCM. Treatment with N-endoglycosidases lowered the molecular mass of chPTHrP binding proteins to 54 kDa in UMR and RCM. In conclusion, skeletal UMR-106 cells and renal cortical membranes of the rat reveal PTH/PTHrP receptors with no apparent tissue specific differences in molecular mass of the polypeptide backbone and polysaccharide chains. Higher affinity of rat PTH(1-34) binding and lower Hill coefficients in kidney compared to bone are consistent with tissue specific receptor-ligand interactions.
Kaufmann
M
M
Department of Orthopaedic Surgery and Medicine, University of Zurich, Switzerland.
Fischer
J A
JA
Muff
R
R
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D012516:Osteosarcoma / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments / Q000494:pharmacology; D010777:Photochemistry; D011506:Proteins / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018016:Receptors, Parathyroid Hormone / Q000378:metabolism*
D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D011506:Proteins; D018016:Receptors, Parathyroid Hormone; C066362:parathyroid hormone-related protein (1-36)amide, N(alpha)-(4-azido-2-nitrophenyl)-Ala(1)-Tyr(36)-