Extracellular calcium-sensing receptor (CASR)

G-protein-coupled receptor that senses changes in the extracellular concentration of calcium ions and plays a key role in maintaining calcium homeostasis (PubMed:7759551, PubMed:8702647, PubMed:8636323, PubMed:8878438, PubMed:17555508, PubMed:19789209, PubMed:21566075, PubMed:22114145, PubMed:23966241, PubMed:25292184, PubMed:25104082, PubMed:26386835, PubMed:25766501, PubMed:22789683). Senses changes from the circulating calcium concentration and modulates the production of parathyroid hormone (PTH) in adrenal glands (By similarity).

The activity of this receptor is mediated by a G-protein that activates a phosphatidylinositol- calcium second messenger system (PubMed:7759551). The G-protein- coupled receptor activity is activated by a co-agonist mechanism: aromatic amino acids, such as Trp or Phe, act concertedly with divalent cations, such as calcium or magnesium, to attain whole receptor activation (PubMed:27434672, PubMed:27386547).