The mechanism of dicyclohexylcarbodiimide (DCCD) and quinine
inhibit K+ transport in rat liver mitochondria.
K. D. Garlid, D. J. DiResta, W. H. Martin and A. D. Beavis (1986)
On the mechanism by which dicyclohexylcarbodiimide (DCCD) and quinine inhibit
K+ transport in rat liver mitochondria. J. Biol. Chem. 261: 1529-1535.
Abstract:
Passive uptake of potassium acetate into the mitochondrial matrix can be induced
by nigericin, a K+/H+ antiporter, or by A23187, a Mg2+/2H+ antiporter. The
latter process is thought to reflect operation of the Mg2+-dependent, endogenous
K+/H+ antiporter, but there is ambiguity with respect to the mechanism of
K+ transport in this assay (Nakashima, R.A., and Garlid, K.D. (1982) J. Biol.
Chem. 257, 9252-9254). Kinetic analysis of potassium acetate transport provides
verification that Mg2+ depletion 1) unmasks the K+/H+ antiporter, 2) opens
up an intrinsic anion uniporter, 3) has no effect on acetic acid transport,
and 4) does not induce high K+ uniport conductance. Mg2+-dependent uptake
of potassium acetate is thereby shown to be mediated specifically by operation
of the endogenous K+/H+ antiporter, as previously proposed. An extension
of this analysis confirms that N,N'-dicyclohexylcarbodiimide and quinine
block potassium acetate uptake via specific action on the K+/H+ antiporter.
These findings support those of a previous study (Martin, W.H., Beavis, A.D.,
and Garlid, K.D. (1984) J. Biol. Chem. 259, 2062-2065) in which binding of
[14C]N,N'-dicyclohexylcarbodiimide to membrane proteins under selective conditions
was used to identify an 82,000-dalton band as the protein responsible for
K+/H+ antiport in mitochondria.