Vacuolar transporters and their essential role in plant metabolism.
Following the unequivocal demonstration that plants contain at least two types of vacuoles, scientists studying this organelle have realized that the plant 'vacuome' is far more complex than they expected. Some fully developed cells contain at least two large vacuoles, with different functions. Remarkably, even a single vacuole may be subdivided and fulfil several functions, which are supported in part by the vacuolar membrane transport systems. Recent studies, including proteomic analyses for several plant species, have revealed the tonoplast transporters and their involvement in the nitrogen storage, salinity tolerance, heavy metal homeostasis, calcium signalling, guard cell movements, and the cellular pH homeostasis. It is clear that vacuolar transporters are an integrated part of a complex cellular network that enables a plant to react properly to changing environmental conditions, to save nutrients and energy in times of plenty, and to maintain optimal metabolic conditions in the cytosol. An overview is given of the main features of the transporters present in the tonoplast of plant cells in terms of their function, regulation, and relationships with the microheterogeneity of the vacuome.
Martinoia
Enrico
E
Institute of Plant Biology, University of Zürich, Zollikerstr. 107, CH-8008 Zürich, Switzerland. enrico.martinoia@botinst.unizh.ch
Maeshima
Masayoshi
M
Neuhaus
H Ekkehard
HE
D001692:Biological Transport; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000378:metabolism*; D019216:Metals, Heavy / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D059828:Plant Cells; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000737:chemistry / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011755:Pyrophosphatases / Q000378:metabolism; D014617:Vacuoles / Q000737:chemistry / Q000378:metabolism*; D015262:Xenobiotics / Q000378:metabolism
D026901:Membrane Transport Proteins; D019216:Metals, Heavy; D010940:Plant Proteins; D015262:Xenobiotics; D011755:Pyrophosphatases; D006180:Proton-Translocating ATPases; D009584:Nitrogen