A voltage-dependent Ca2+ homeostat operates in the plant vacuolar membrane.
Cytosolic calcium signals are evoked by a large variety of biotic and abiotic stimuli and play an important role in cellular and long distance signalling in plants. While the function of the plasma membrane in cytosolic Ca2+ signalling has been intensively studied, the role of the vacuolar membrane remains elusive. A newly developed vacuolar voltage clamp technique was used in combination with live-cell imaging, to study the role of the vacuolar membrane in Ca2+ and pH homeostasis of bulging root hair cells of Arabidopsis. Depolarisation of the vacuolar membrane caused a rapid increase in the Ca2+ concentration and alkalised the cytosol, while hyperpolarisation led to the opposite responses. The relationship between the vacuolar membrane potential, the cytosolic pH and Ca2+ concentration suggests that a vacuolar H+ /Ca2+ exchange mechanism plays a central role in cytosolic Ca2+ homeostasis. Mathematical modelling further suggests that the voltage-dependent vacuolar Ca2+ homeostat could contribute to calcium signalling when coupled to a recently discovered K+ channel-dependent module for electrical excitability of the vacuolar membrane.
['Dindas|Julian|J|0000-0003-3078-4865', 'Dreyer|Ingo|I|0000-0002-2781-0359', 'Huang|Shouguang|S|0000-0001-7007-0301', 'Hedrich|Rainer|R|0000-0003-3224-1362', 'Roelfsema|M Rob G|MRG|0000-0002-4076-4246']
D017360:Arabidopsis D029681:Arabidopsis Proteins D002118:Calcium D015220:Calcium Channels D020013:Calcium Signaling D003600:Cytosol D014617:Vacuoles
vacuolar membrane calcium signalling voltage clamp Arabidopsis thaliana R-GECO1 cytosolic Ca2+ reporter TPC1 channel computational cell biology cpYFP cytosolic pH reporter