Parathyroid hormone receptors in avian bone cells.

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Abstract
Binding of synthetic bovine parathyroid hormone (1-34) [bPTH-(1-34)] to embryonic chicken bone cells in monolayer culture was demonstrated. The binding sites have qualitative and quantitative characteristics of a physiologically important PTH receptor. At apparent steady state (60 min at 24.degree. C), 5-10% of electrolytically labeled, receptor-purified 125I-labeled bPTH-(1-34) bound specifically to the cells whereas nonspecific binding was less than 1% of the added labeled hormone. Scatchard analysis showed a single order of PTH binding sites (Kd = 0.6 nM) with .apprx. 10,000 sites per cell. In this bone cell system, PTH bound to its binding site and stimulated cAMP accumulation over the same concentration range. Bovine PTH-(1-84) bound to the cells with the same apparent affinity as bPTH-(1-34).