Structural and functional aspects of calcium homeostasis in eukaryotic cells

The maintenance of a low cytosolic free-Ca2+ concentration, ([Ca2+]i) is a common feature of all eukaryotic cells. For this purpose a variety of mechanisms have developed during evolution to ensure the buffering of Ca2+ in the cytoplasm, its extrusion from the cell and/or its accumulation within organelles. Opening of plasma membrane channels or release of Ca2+ from intracellular pools leads to elevation of [Ca2+]i; as a result, Ca2+ binds to cytosolic proteins which translate the changes in [Ca2+]i into activation of a number of key cellular functions. The purpose of this review is to provide a comprehensive description of the structural and functional characteristics of the various components of [Ca2+]i homeostasis in eukaryotes.