The Calcium-Sensing Receptor in Intestinal Cells

The calcium-sensing receptor (CaSR or CaR) was first identified in the bovine parathyroid gland. Its primary function is to regulate calcium homeostasis in the body. However, CaSR is expressed in a variety of tissues that are not directly related to calcium homeostasis. In addition to calcium ions, various compounds such as l-amino acids, polyamines, basic polypeptides, gamma glutamyl peptides, and other peptides, also activate CaSR in an allosteric manner. Its broad ligands and wide expression profile suggest multiple functions of CaSR in different tissues. This chapter reviews the functions of CaSR in the gastrointestinal tract. Specifically, a role for CaSR in luminal nutrient sensing in the enteroendocrine system is described.