PMID- 12244254
OWN - NLM
STAT- Publisher
LR  - 20191120
IS  - 1532-298X (Electronic)
IS  - 1040-4651 (Print)
IS  - 1040-4651 (Linking)
VI  - 6
IP  - 5
DP  - 1994 May
TI  - Two Voltage-Gated, Calcium Release Channels Coreside in the Vacuolar Membrane of 
      Broad Bean Guard Cells.
PG  - 685-694
AB  - 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.
FAU - Allen, G J
AU  - Allen GJ
AD  - Department of Biology, University of York, York, YO1 5DD United Kingdom.
FAU - Sanders, D
AU  - Sanders D
LA  - eng
PT  - Journal Article
PL  - England
TA  - Plant Cell
JT  - The Plant cell
JID - 9208688
PMC - PMC160468
EDAT- 1994/05/01 00:00
MHDA- 2002/09/24 06:00
PMCR- 1995/05/01
CRDT- 1994/05/01 00:00
PHST- 1994/05/01 00:00 [pubmed]
PHST- 2002/09/24 06:00 [medline]
PHST- 1994/05/01 00:00 [entrez]
PHST- 1995/05/01 00:00 [pmc-release]
AID - 6/5/685 [pii]
AID - 10.1105/tpc.6.5.685 [doi]
PST - ppublish
SO  - Plant Cell. 1994 May;6(5):685-694. doi: 10.1105/tpc.6.5.685.