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, the majority of which belong to the EF‐hand superfamily of calcium‐binding proteins. EF‐hand proteins are classified into calcium signal sensors and modulators. The signal modulators fine‐tune the shape and duration of calcium signals. The calcium 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 intracellular signalling pathways.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 binding of calcium by EF hand calcium sensing proteins induces structural changes that activate the protein for interaction with other target proteins.EF‐hand calcium‐binding proteins play important roles in health and disease.