TY - JOUR
T1 - A large, voltage-dependent channel, isolated from mitochondria by water-free chloroform extraction
AU - Pavlov, Evgeny
AU - Zakharian, Eleonora
AU - Bladen, Christopher
AU - Diao, Catherine T. M.
AU - Grimbly, Chelsey
AU - Reusch, Rosetta N.
AU - French, Robert J.
PY - 2005
Y1 - 2005
N2 - We examined ion channels derived from a chloroform extract of isolated, dehydrated rat liver mitochondria. The extraction method was previously used to isolate a channel-forming complex containing poly-3-hydroxybutyrate and calcium polyphosphate from Escherichia coli. This complex is also present in eukaryotic membranes, and is located primarily in mitochondria. Reconstituted channels showed multiple subconductance levels and were voltage-dependent, showing an increased probability of higher conductance states at voltages near zero. In symmetric 150 mM KCl, the maximal conductance of the channel ranged from 350 pS to 750 pS. For voltages >±60 mV, conductance fluctuated in the range of ∼50–∼200 pS. In the presence of a 1:3 gradient of KCl, at pH = 7.4, selectivity periodically switched between different states ranging from weakly anion-selective (Vrev ∼ −15 mV) to ideally cation-selective (Vrev ∼ +29 mV), without a significant change in its conductance. Overall, the diverse, but highly reproducible, channel activity most closely resembled the behavior of the permeability transition pore channel seen in patch-clamp experiments on native mitoplasts. We suggest that the isolated complex may represent the ion-conducting module from the permeability transition pore.
AB - We examined ion channels derived from a chloroform extract of isolated, dehydrated rat liver mitochondria. The extraction method was previously used to isolate a channel-forming complex containing poly-3-hydroxybutyrate and calcium polyphosphate from Escherichia coli. This complex is also present in eukaryotic membranes, and is located primarily in mitochondria. Reconstituted channels showed multiple subconductance levels and were voltage-dependent, showing an increased probability of higher conductance states at voltages near zero. In symmetric 150 mM KCl, the maximal conductance of the channel ranged from 350 pS to 750 pS. For voltages >±60 mV, conductance fluctuated in the range of ∼50–∼200 pS. In the presence of a 1:3 gradient of KCl, at pH = 7.4, selectivity periodically switched between different states ranging from weakly anion-selective (Vrev ∼ −15 mV) to ideally cation-selective (Vrev ∼ +29 mV), without a significant change in its conductance. Overall, the diverse, but highly reproducible, channel activity most closely resembled the behavior of the permeability transition pore channel seen in patch-clamp experiments on native mitoplasts. We suggest that the isolated complex may represent the ion-conducting module from the permeability transition pore.
U2 - 10.1529/biophysj.104.057281
DO - 10.1529/biophysj.104.057281
M3 - Article
C2 - 15695627
SN - 0006-3495
VL - 88
SP - 2614
EP - 2625
JO - Biophysical Journal
JF - Biophysical Journal
IS - 4
ER -