Shaping the calcium signature

Introduction 276 Ca2+ signalling pathways 276 Shaping Ca2+ signatures 278 Ca2+ influx channels 278 Ca2+ influx channels as modulators of Ca2+ signatures 281 Ca2+ efflux transporters 282 Ca2+ efflux transporters as modulators of Ca2+ signatures 284 The shaping of noncytosolic Ca2+ signatures 285 Future insights into the role of Ca2+ oscillators from modelling studies 287 Conclusions and perspectives 288 Acknowledgements 288 References 288 In numerous plant signal transduction pathways, Ca2+ is a versatile second messenger which controls the activation of many downstream actions in response to various stimuli. There is strong evidence to indicate that information encoded within these stimulus-induced Ca2+ oscillations can provide signalling specificity. Such Ca2+ signals, or 'Ca2+ signatures', are generated in the cytosol, and in noncytosolic locations including the nucleus and chloroplast, through the coordinated action of Ca2+ influx and efflux pathways. An increased understanding of the functions and regulation of these various Ca2+ transporters has improved our appreciation of the role these transporters play in specifically shaping the Ca2+ signatures. Here we review the evidence which indicates that Ca2+ channel, Ca2+-ATPase and Ca2+ exchanger isoforms can indeed modulate specific Ca2+ signatures in response to an individual signal. New Phytologist (2009) 181: 275-294doi: 10.1111/j.1469-8137.2008.02682.x.