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Calcium (Ca2+) efflux transporters remove Ca2+ from the cytosol of the cell either by transporting it out of the cell across the plasma membrane or into internal organelles. These transporters, which include Ca2+-ATPases and Ca2+/H+ antiporters, have a critical role in preventing Ca2+ toxicity, maintaining cytosolic Ca2+ at a low resting level, and transferring Ca2+ to specific cellular locations where it is required. Many genes encoding plant Ca2+-ATPases and Ca2+/H+ antiporters have now been identified and characterised to elucidate their biochemical and genetic features. Furthermore, the use of gene knockouts has begun to provide evidence for an involvement of these Ca2+ transporters in Ca2+-signaling networks and in various aspects of plant development. [ABSTRACT FROM AUTHOR]

Calcium is an essential plant nutrient, thus the influx of Ca2+ into plant cells is a critical process. In addition, the efflux of Ca2+ out of a cell is important to prevent toxicity resulting from Ca2+ excess, and to modulate levels of cytosolic Ca2+ required for signaling functions. Biochemical and genetic analysis of plants has begun to identify the complement of Ca2+-permeable channels and Ca2+-ATPases Ca2+-ATPase that function in Ca2+ flux across the plasma membrane. In addition to understanding the mechanisms of plasma membrane Ca2+ transport, some of the specific functions of these pathways are now emerging. Comparative genomics of higher plant, algal and moss species has identified significant variation in the mechanisms of plasma membrane Ca2+ transport between higher and lower plants, and provides insight into the evolution of Ca2+ transport processes. [ABSTRACT FROM AUTHOR]