Ca2+‐storage organelles

Intracellular Ca2+‐storage organelles are found in virtually all eukaryotic cells. They play an important role in the regulation of the cytosolic free Ca2+ concentration and, thereby, in the regulation of cellular activity. Ca2+‐storage organelles consist, in the simplest model of a Ca2+ pump, of a Ca2+‐storage protein and a Ca2+‐release channel. The primary structure of these functionally important proteins of Ca2+‐storage organelles is similar in different cell types and conserved through evolution. In contrast, their spatial arrangement and, thus, the architecture of Ca2+‐storage organelles may vary dramatically from one cell type to another.