Structure of the PTH-1 Receptor (IMAGE) University of Zurich Caption The receptor is the key regulatory switch controlling calcium release from bones, and thus a prime target for developing new drugs for the treatment of osteoporosis. The receptor consists of an extracellular part (purple) and a part that resides in the membrane (green). Parathyroid hormone (orange) activates the receptor. Credit University of Zurich Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.