H<sup>+</sup>/site ratio and steady state distribution of divalent cations in mitochondria

Gf, Azzone; Pozzan, Tullio; Massari, Stefano; Bragadin, Marcantonio; Dell’Antone, Paolo

doi:10.1016/0014-5793(77)80264-0

Cited by 46 publications

(20 citation statements)

References 23 publications

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“…It seems likely, therefore, that calcium-/3-hydroxybutyrate symport occurs via a separate lanthanide-sensitive porter that is independent of the lanthanide-sensitive (Ca2)4+-HPO 2-symporter. The observations of this and our previous two papers [ 1,2], together with work by Azzone et al [7], indicate that calcium and some other bivalent cations including strontium may permeate the crista~ membrane of rat liver mitochondria with an electric charge stoicheiometry corresponding to <--Ca r via at least two systems that are sensitive to lanthanides but insensitive to NEM. One is the (Ca2)4+-HPO~ -symporter described previously [1,2] and the other is a Ca2÷-/3-hydroxybutyrate-symporter of unknown but equal valency for Ca 2÷ and/3-hydroxybutyratedescribed in the present paper.…”

Section: Anion Specificity Of Bivalent Cation Importsupporting

confidence: 65%

Lanthanide‐sensitive calcium—monocarboxylate symport in rat liver mitochondria

Moyle

Mitchell

1977

FEBS Letters

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Section: Anion Specificity Of Bivalent Cation Importsupporting

confidence: 65%

Lanthanide‐sensitive calcium—monocarboxylate symport in rat liver mitochondria

Moyle

Mitchell

1977

FEBS Letters

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“…that the Ca2+ uniporter A of Fig. 14 probably does not exist in mitochondria, but that calcium is probably translocated by the symporters B and C , and possibly by other similar systems yet to be discovered, is not generally accepted. Indeed, evidence and arguments against our experimental findings and interpretations have been presented by Lehninger and colleagues [95,103], by Azzone and colleagues [104], and by Crompton, Hediger and Carafoli [105]. Brian Chappell has told me privately that his paper during this FEBS meeting will also describe observations from which he concludes that calcium is translocated, not with one positive charge, as we [96] and Akerman [97] have found, but with two positive charges, as was formerly supposed.…”

Section: Coupling Between Chemiosmotic and Purely Osmotic Reactionsmentioning

confidence: 50%

Compartmentation and Communication in Living Systems. Ligand Conduction: a General Catalytic Principle in Chemical, Osmotic and Chemiosmotic Reaction Systems

Mitchell

1979

European Journal of Biochemistry

350

132

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Chemical reactions, like osmotic reactions, are transport processes when looked at in detail. Chemical catalysis by enzymes or catalytic carriers, and osmotic catalysis by porters, may be conceived as occurring by specific ligand‐conduction mechanisms. In chemiosmotic reaction systems, the pathways of specific ligand conduction are spatially orientated through anisotropic enzyme and catalytic carrier complexes in which the reactions of chemical group transfer occur as vectorial diffusion processes of group translocation down gradients of group potential that represent real spatially‐directed fields of chemical force. Thus, it is easier to explain biochemistry in terms of transport than it is to explain transport in terms of biochemistry.

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“…All chemicals were of analytical grade. Matrix pH was determined on the distribution of [3H]acetate or of [14C]methylamine [21]. Mitochondria were incubated under the specified conditions in the presence of either 10 pM Calcium Influx.…”

Section: Methodsmentioning

confidence: 99%

ΔpH Induced Calcium Fluxes in Rat Liver Mitochondria

Bernardi¹,

Azzone²,

Veronese³

1979

European Journal of Biochemistry

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The paper reports an investigation on ΔpH‐driven Ca2+ fluxes in rotenone‐treated rat liver mitochondria. The H+ concentration gradient (acidic inside) required to drive Ca2+ influx is obtained from the K+ concentration gradient through a H+/K+ exchange. The rate of H+/K+ exchange is very low in native mitochondria and is markedly enhanced by the electroneutral ionophore nigericin. The rate of Ca2+ influx depends on the rate of generation of ΔpH; it is negligible in native mitochondria and fast after nigericin. The process of ΔpH‐driven Ca2+ influx shows three basic features. First, the rate of Ca2+ influx is markedly increased by the addition of uncouplers. Second, the rate of Ca2+ influx is inhibited by ruthenium red with the same sensitivity as the processes driven by the H+ pump or K+ diffusion. The electroneutral H+/Ca2+ ionophore A23187 restores Ca2+ influx in mitochondria inhibited by ruthenium red. Third, both rate and extent of ΔpH‐driven Ca2+ influx are inhibited by the addition of weak bases but not of weak acids. The process of ΔpH‐driven Ca2+ influx is accompanied by H+ efflux. A correlation also exists between generation of ΔpH (acidic inside) due to H+/K+ exchange and utilization of ΔpH due to H+/Ca2+ exchange. The process of ΔpH‐driven, A23187‐catalyzed, H+/Ca2+ exchange is not preceeded by rapid H+/K+ exchange in the absence of nigericin. After termination of the phase of Ca2+ influx a phase of Ca2+ efflux ensues. Ca2+ efflux is not coupled to H+ or K+ reentry and is completely inhibited by ruthenium red. Ca2+ efflux is not observed when Ca2+ transport is catalyzed by A23187 in mitochondria inhibited by ruthenium red. Furthermore A23187 abolishes Ca2+ efflux also when Ca2+ influx occurs in the absence of ruthenium red. The data suggest that the ΔpH‐driven Ca2+ influx and the subsequent Ca2+ efflux take place through the native carrier as electrical uniport.

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H⁺/site ratio and steady state distribution of divalent cations in mitochondria

Cited by 46 publications

References 23 publications

Lanthanide‐sensitive calcium—monocarboxylate symport in rat liver mitochondria

Lanthanide‐sensitive calcium—monocarboxylate symport in rat liver mitochondria

Compartmentation and Communication in Living Systems. Ligand Conduction: a General Catalytic Principle in Chemical, Osmotic and Chemiosmotic Reaction Systems

ΔpH Induced Calcium Fluxes in Rat Liver Mitochondria

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H+/site ratio and steady state distribution of divalent cations in mitochondria

Cited by 46 publications

References 23 publications

Lanthanide‐sensitive calcium—monocarboxylate symport in rat liver mitochondria

Lanthanide‐sensitive calcium—monocarboxylate symport in rat liver mitochondria

Compartmentation and Communication in Living Systems. Ligand Conduction: a General Catalytic Principle in Chemical, Osmotic and Chemiosmotic Reaction Systems

ΔpH Induced Calcium Fluxes in Rat Liver Mitochondria

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H⁺/site ratio and steady state distribution of divalent cations in mitochondria