EF‐hand Calcium‐binding Proteins

AbstractCalcium and the proteins that bind to it play important roles in normal physiological processes and have been implicated in a variety of diseases. The importance of calcium is due mainly to its role as a second messenger in signal transduction. The calcium signal is mediated and controlled by many proteins in the cell, the majority of which belong to the EF‐hand super‐family of calcium‐binding proteins. EF‐hand proteins are classified into calcium signal sensors and modulators. The calcium modulators fine‐tune the shape and duration of calcium signals. The sensors undergo significant conformational changes when they bind calcium, which exposes new surfaces that interact with target proteins. Together, EF‐hand calcium‐binding proteins serve in the critical process of converting the ionic signal into activation of signalling pathways in cells.Key Concepts:The EF‐hand is a helix–loop–helix structural motif.Calcium binds to oxygen atoms from the backbone and side‐chain atoms of specific amino acids in EF‐hand calcium‐binding proteins.The basic structural and functional unit of EF‐hand calcium‐binding proteins is a pair of EF‐hand motifs.EF‐hand calcium‐binding proteins can be classified as sensors or modulators of calcium signals.EF‐hand calcium senor proteins need to transition from an ‘off ’ state at the resting level of calcium in the cell, to an ‘on’ (activated) state when calcium signals increase the concentration of calcium.The activation of EF‐hand calcium sensor proteins results from changes in structure induced by the binding of calcium ions.The binding of calcium activates EF‐hand calcium sensor proteins, triggering their interaction with target proteins.