PTHR

PTHR is a G protein-coupled receptor (GPCR) that regulates calcium and phosphate homeostasis, bone formation, and renal function. PTHR is activated by PTH, PTH-related peptide (PTHrP), and tuberoinfundibular peptide of 39 residues (TIP39), which activates G-protein and initiates downstream signaling cascades such as Gαs/cAMP/PKA signaling pathway. PTHR promotes the release of calcium ions from bones and increases the kidneys' reabsorption of calcium ions, thereby maintaining blood calcium homeostasis. PTHR also reduces blood phosphorus levels by promoting renal phosphorus excretion. PTHR participates in bone formation, cartilage development, and the development of the pancreas, teeth and mammary glands. PTHR exists in three isoforms, PTH1R, PTH2R and PTH3R. PTH1R has a high affinity for PTH and PTHrP and is the main receptor for calcium homeostasis regulation. PTH2R has a high affinity for TIP39 and is involved in the functional regulation of the central nervous system. PTH3R is mainly expressed in non-mammalian vertebrates and has a higher affinity for PTHrP. PTHR dysfunction could lead to Blomstrand’s lethal chondroplasia, Ollier’s disease, Jansen’s metaphyseal chondroplasia, hypoparathyroidism, hyperparathyroidism and osteoporosis^[1][2].

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