Calcium-binding proteins are proteins that participate in calcium cell signaling pathways by binding to Ca2+, the calcium ion that plays an important role in many cellular processes. Calcium-binding proteins have specific domains that bind to calcium and are known to be heterogeneous.
One of the functions of calcium binding proteins is to regulate the amount of free (unbound) Ca2+ in the cytosol of the cell.[1] The cellular regulation of calcium is known as calcium homeostasis.