KalziumsensingRezeptor

KalziumSensingRezeptor, also known as CaSR, is a cell surface receptor that plays a crucial role in calcium homeostasis. It is a member of the G protein-coupled receptor (GPCR) superfamily. The CaSR is primarily expressed in the parathyroid glands, kidneys, and gastrointestinal tract. Its main function is to detect changes in the extracellular calcium concentration and signal accordingly to maintain blood calcium levels within a narrow physiological range.

When extracellular calcium levels rise, CaSR is activated, leading to a decrease in parathyroid hormone (PTH) secretion from the parathyroid glands. PTH is a key hormone in raising blood calcium levels. Conversely, when extracellular calcium levels fall, CaSR is inhibited, resulting in increased PTH secretion. In the kidneys, CaSR influences calcium reabsorption, and in the gut, it may affect calcium absorption.

Mutations in the CaSR gene can lead to various disorders. Loss-of-function mutations are associated with familial hypocalciuric hypercalcemia (FHH), a condition characterized by high blood calcium levels and low urinary calcium excretion. Gain-of-function mutations can cause autosomal dominant hypocalcemia, leading to low blood calcium levels. The study of CaSR is vital for understanding calcium metabolism and developing therapeutic strategies for related diseases.