Incorporation in lipid bilayers of a large conductance cationic channel from mitochondrial membranes.
Membranes from subcellular fractions of adrenal medulla were incorporated in phospholipid bilayers formed at the tip of microelectrodes. Current fluctuations recorded in the presence of a transmembrane potential revealed the existence of a voltage-dependent channel of large conductance. This channel is characterized by fast kinetics and four conductance levels separated by jumps of 100, 220 and 220 pS in 150 mM NaCl. It is permeant to Na+,K+, tetraethylammonium, Cl- and acetate and has some cation selectivity. Exposure to trypsin or pronase abolished the voltage-dependence. Upon subcellular fractionation, the activity was found to be associated with mitochondria. A similar activity was observed in mitochondrial fractions from other organs. By its kinetics, its selectivity and its potential-dependence, this channel differs from the voltage-dependent anion channel of outer mitochondrial membranes.
Thieffry
M
M
Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS, France.
Chich
J F
JF
Goldschmidt
D
D
Henry
J P
JP
D000313:Adrenal Medulla / Q000378:metabolism; D000818:Animals; D002412:Cations; D002417:Cattle; D004553:Electric Conductivity; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D051381:Rats
D002412:Cations; D007473:Ion Channels; D008051:Lipid Bilayers