STRUCTURE AND TISSUE-SPECIFIC EXPRESSION OF THE PARATHYROID-HORMONE RECEPTOR GENE

The parathyroid hormone receptor is a member of a vast family of G pro tein-coupled receptors containing seven transmembrane do-mains. It is the primary target of two ligands, parathyroid hormone (PTH) and PTH r elated peptide (PTHrP), and as such controls a number of physiological responses. Signaling between PTHrP and the receptor is essential for normal skeletal development in the embryo. In the adult, PTH regulates extracellular fluid calcium levels by interacting with receptors expr essed in bone and kidney. The determination of the structure of the mo use parathyroid hormone receptor gene has shown that it is a member of a subfamily of conserved peptide hormone receptors. The gene is expre ssed in several tissues,and its expression is controlled by at least t wo promoters. Activity of the upstream promoter is specific to kidney. Our studies provide evidence for the mechanisms which regulate the ex pression of the parathyroid hormone receptor in multiple tissues in th e mouse, and may provide a genetic basis for specific defects in calci um homeostasis seen in humans.