title: The ins and outs of cellular Ca(2+) transport.
abstract: The cytoplasmic Ca(2+) signals that participate in nearly all aspects of plant growth and development encode information as binary switches or information-rich signatures. They are the result of influx (thermodynamically passive) and efflux (thermodynamically active) activities mediated by membrane transport proteins. On the influx side, confirming the molecular identities of Ca(2+)-permeable channels is still a major research topic. Cyclic nucleotide-gated channels and glutamate receptor-like channels are candidates well supported by evidence. On the efflux side, CAX antiporters and P-type ATPase pumps are the principal molecular entities. Both of these active transporters load Ca(2+) into specific compartments and have the potential to reduce the magnitude and duration of a Ca(2+) transient. Recent studies indicate calmodulin-activated Ca(2+) pumps in endomembrane systems can dampen the magnitude and duration of a Ca(2+) transient that could otherwise grow into a Ca(2+) cell death signature. An important challenge following molecular characterization of the influx and efflux pathways is to understand how they are coordinately regulated to produce a Ca(2+) switch or encode specific information into a Ca(2+) signature.
authors.affiliation: University of Wisconsin-Madison, Department of Botany, Madison, WI 53706, USA. spalding@wisc.edu
authors.forename: Edgar P
authors.initials: EP
authors.lastname: Spalding
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Harper
mesh_terms: D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002451:Cell Compartmentation; D008954:Models, Biological; D015398:Signal Transduction
chemical_list: D015220:Calcium Channels; D002118:Calcium