Degrading activity for human parathyroid hormone [PTH-(1-84)] in rat osteoblast-like osteosarcoma cell line UMR106.
The degrading activity for human parathyroid hormone [hPTH-(1-84)] was studied in a rat osteoblast-like osteosarcoma cell line UMR106. At 37 C,UMR106 cells degraded hPTH-(1-84) into fragments in a time-dependent manner, which was shown by a radioimmunoassay with the use of antibody recognizing the C-terminal and middle regions of PTH molecule, whereas the degradation was completely suppressed at 4 C and failed to occur in the absence of the cells. The Lineweaver-Burk plot of this degrading activity at 37 C showed a fairly good linearity and gave a Km value of 5.1 X 10(-7) M. Reverse-phase high-performance liquid chromatography (HPLC) analysis of immunoreactive PTH fragments in the medium disclosed two peaks aside from intact PTH, indicating a limited PTH-hydrolyzing activity of UMR106 cells cleaving the molecule between at least two separate positions. This study suggests the possible involvement of osteoblasts on the metabolism of intact PTH.
D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D010006:Osteoblasts / Q000201:enzymology*; D012516:Osteosarcoma; D010281:Parathyroid Hormone / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D051381:Rats
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D000242:Cyclic AMP