Down-regulation of adenylate cyclase-coupled response to native bovine parathyroid hormone and fragments in the osteoblast-like cell line UMR-106

Abstract

1. 1. Parathyroid hormone-induced down-regulation was studied in the osteosarcoma cell line UMR-106. 2. 2. A maximal priming does of bPTH (1–84) down-regulated PTH-responsiveness to 40% of its initial value; bPTH (1–41) was less effective than bPTH (1–84), whereas bPTH (42–84) had no effect, alone or in combination with bPTH (1–41). 3. 3. A tentative model for the function of different domains of parathyroid hormone in down-regulation is suggested.