Calmodulin

Calmodulin (CaM), the member of EF-hand proteins superfamily, is a highly conserved eukaryotic Ca²⁺ sensor protein. Upon cellular stimulation, different mechanisms lead to transient intracellular increases in Ca²⁺ concentrations that initiate different protein activities. Most proteins are devoid of Ca²⁺ binding sites, requiring a mediator to respond to this cation. The ability to transmit conformational changes to a large and diverse array of proteins in response to Ca²⁺ oscillations, coordinating the activity of hundreds of proteins, makes calmodulin the most important Ca²⁺ signal transducer in eukaryotic cells. When Ca²⁺ binds to calmodulin it forms the Ca²⁺/calmodulin complex which then interacts with other proteins in the cell. These proteins are enzymes and effector proteins involved in a variety of cellular and physiological processes. The Ca²⁺/calmodulin complex can also regulate processes directly.