Hilary M. Docherty1, David A. Heath
1Department of Medicine, University of Birmingham, Queen Elizabeth Hospital.
Tóm tắt
ABSTRACT
The extensive chromatographic characterization of four parathyroid hormone (PTH)-like proteins in a human bronchial carcinoid tumour associated with humoral hypercalcaemia and severe osteitis fibrosa is described. PTH-like bioactivity was detected in acetic acid extracts of the tumour using an in-vitro osteosarcoma cell bioassay. The active tumour proteins were positively charged at physiological pH and had apparent Mr of approximately 29 000, 16 000, 4000–9000 and < 4000. The proteins were immunologically distinct from PTH, but each stimulated PTH-sensitive adenylate cyclase in cultured osteoblastic cells. There was no evidence of PTH gene expression by the tumour. These proteins represent different molecular forms of PTH-related protein.
