Encyclopedia of Life Sciences

Abstract

The calcium ion (Ca2+) is a versatile intracellular messenger. It provides dynamic regulation of vast array of cellular processes such as gene transcription, differentiation and contraction. Ca2+ signals range from microsecond, nanoscopic events to intercellular waves lasting for many seconds. This diversity of Ca2+ signals arises from the wide assortment of Ca2+ transport and Ca2+ buffering processes employed by cells. Additional diversity in Ca2+ signalling stems from the ability of cells to utilise different sources of Ca2+. The cytosol is the principal Ca2+ signalling compartment. When Ca2+ ions enter the cytosol they interact with numerous Ca2+-binding proteins, thereby leading to activation, or inhibition, of cellular processes. Specificity is achieved by regulating the spatial and kinetic properties of Ca2+ signal. In this way, many concurrent Ca2+-sensitive cellular processes can be discretely regulated. A number of pathologies have been related to the breakdown of cellular Ca2+ homoeostasis or to aberrant Ca2+ signalling.