|
THE PLANT CELL, Vol 6, Issue 5 685-694, Copyright © 1994 by American Society of Plant Biologists
Two Voltage-Gated, Calcium Release Channels Coreside in the Vacuolar Membrane of Broad Bean Guard Cells
G. J. Allen and D. Sanders
Department of Biology, University of York, York, YO1 5DD United Kingdom
Voltage-gated, Ca2+ release channels have been characterized at the
vacuolar membrane of broad bean guard cells using patch clamps of excised,
inside-out membrane patches. The most prevalent Ca2+ release channel had a
conductance of 27 pS over voltages negative of the reversal potential
(Erev) (cytosol referenced to vacuole), with 5,10, or 20 mM Ca2+ as the
charge carrier on the vacuolar side and 50 mM K+ on the cytosolic side. The
single-channel current saturated at ~2.6 pA. The relative permeability of
the channel was in the range of a Pca2+:Pk+ ratio of 6:1. Divalent cations
could act as charge carriers on the vacuolar side with a conductance series
of Ba2+ > Mg2+ > Sr2+ > Ca2+ and a selectivity sequence of Ca2+
[approximately equals to] Ba2+ [approximately equals to] Sr2+ > Mg2+.
The channel was gated open by cytosol-negative (physiological)
transmembrane voltages, increases in vacuolar Ca2+ concentration, and
increases in the vacuolar pH. The channel was potently inhibited by the
Ca2+ channel blockers Gd3+ (half-maximal inhibition at 10.3 [mu]M) and
nifedipine (half-maximal inhibition at 77 [mu]M). The stilbene derivative
4,4[prime]-diisothiocyano-2,2[prime]-stilbene disulfonate was also
inhibitory (half-maximal inhibition for a 4-min incubation period at
6.3[mu]M). The 27-pS channel coresides in individual guard cell vacuoles
with a less frequently observed 14-pS Ca2+ release channel that had
similar, although not identical, voltage dependence and gating
characteristics and a lower selectivity for Ca2+ over K+. The requirement
for two channels with a similar function at the vacuolar membrane of guard
cells is discussed.
This article has been cited by other articles:

|
 |

|
 |
 
I. I. Pottosin and G. Schonknecht
Vacuolar calcium channels
J. Exp. Bot.,
May 1, 2007;
58(7):
1559 - 1569.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
G. M. VOLK, L. J. GOSS, and V. R. FRANCESCHI
Calcium Channels are Involved in Calcium Oxalate Crystal Formation in Specialized Cells of Pistia stratiotes L.
Ann. Bot.,
June 1, 2004;
93(6):
741 - 753.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
P. Dietrich, D. Sanders, and R. Hedrich
The role of ion channels in light-dependent stomatal opening
J. Exp. Bot.,
October 1, 2001;
52(363):
1959 - 1967.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
L. Navazio, P. Mariani, and D. Sanders
Mobilization of Ca2+ by Cyclic ADP-Ribose from the Endoplasmic Reticulum of Cauliflower Florets
Plant Physiology,
April 1, 2001;
125(4):
2129 - 2138.
[Abstract]
[Full Text]
|
 |
|

|
 |

|
 |
 
E. Martinoia, A. Massonneau, and N. Frangne
Transport Processes of Solutes across the Vacuolar Membrane of Higher Plants
Plant Cell Physiol.,
November 1, 2000;
41(11):
1175 - 1186.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
D. Sanders, C. Brownlee, and J. F. Harper
Communicating with Calcium
PLANT CELL,
April 1, 1999;
11(4):
691 - 706.
[Full Text]
|
 |
|

|
 |

|
 |
 
B. Klüsener and E. W. Weiler
A Calcium-Selective Channel from Root-Tip Endomembranes of Garden Cress
Plant Physiology,
April 1, 1999;
119(4):
1399 - 1406.
[Abstract]
[Full Text]
|
 |
|

|
 |

|
 |
 
C. P. Leckie, M. R. McAinsh, G. J. Allen, D. Sanders, and A. M. Hetherington
Abscisic acid-induced stomatal closure mediated by cyclic ADP-ribose
PNAS,
December 22, 1998;
95(26):
15837 - 15842.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
K. S. Schumaker and M. J. Gizinski
1,4-Dihydropyridine Binding Sites in Moss Plasma Membranes
J. Biol. Chem.,
October 6, 1995;
270(40):
23461 - 23467.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
G. Allen, Muir SR, and D Sanders
Release of Ca2+ from individual plant vacuoles by both InsP3 and cyclic ADP-ribose
Science,
May 5, 1995;
268(5211):
735 - 737.
[Abstract]
[PDF]
|
 |
|

|
 |

|
 |
 
C. M. Calvert and D. Sanders
Inositol Trisphosphate-dependent and -independent Ca[IMAGE] Mobilization Pathways at the Vacuolar Membrane of Candida albicans
J. Biol. Chem.,
March 31, 1995;
270(13):
7272 - 7280.
[Abstract]
[Full Text]
[PDF]
|
 |
|
|
|