Calcium signalling - an overview

Calcium (Ca2+) is an almost universal intracellular messenger controlling a diverse range of cellular processes, such as gene transcription (see Mells trom and Naranjo, this issue), muscle contraction and cell proliferation. T he ability of a simple ion such as Ca2+ to play a pivotal role in cell biol ogy results from the facility that cells have to Ca2+ signals in the dimens ions of space, time and shape Ca2+ signals. To generate the variety of obse rved Ca2+ signals, different cell types employ components selected from a C a2+ signalling 'toolkit', which comprizes an array of signalling, homeostat ic and sensory mechanisms. By mixing and marching components from the toolk it, cells can obtain Ca2+ signals that suit their physiology.