Primary Structure of the Cytochrome c from the Snapping Turtle, Chelydra Serpentina<sup>*</sup>

Chan, S.K.; Tulloss, I.; Margoliash, E.

doi:10.1021/bi00872a016

Cited by 34 publications

(13 citation statements)

References 35 publications

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“…These conductances correspond to estimated pore diameters of 3.3-5.4 nm without and 4.1-8.1 nm with access resistance. The diameter of cytochrome c is 3-3.4 nm (6). Thus the MAC pore is likely large enough to permit the passage of cytochrome c. MAC with similar conductances responded when the pore was probed with ribonuclease A (3-3.8 nm diameter) (3) (Fig.…”

Section: Discussionmentioning

confidence: 94%

Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC

Guo

Pietkiewicz

Pavlov³

et al. 2004

American Journal of Physiology-Cell Physiology

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Recent studies indicate that cytochrome c is released early in apoptosis without loss of integrity of the mitochondrial outer membrane in some cell types. The high-conductance mitochondrial apoptosis-induced channel (MAC) forms in the outer membrane early in apoptosis of FL5.12 cells. Physiological (micromolar) levels of cytochrome c alter MAC activity, and these effects are referred to as types 1 and 2. Type 1 effects are consistent with a partitioning of cytochrome c into the pore of MAC and include a modest decrease in conductance that is dose and voltage dependent, reversible, and has an increase in noise. Type 2 effects may correspond to "plugging" of the pore or destabilization of the open state. Type 2 effects are a dose-dependent, voltage-independent, and irreversible decrease in conductance. MAC is a heterogeneous channel with variable conductance. Cytochrome c affects MAC in a pore size-dependent manner, with maximal effects of cytochrome c on MAC with conductance of 1.9-5.4 nS. The effects of cytochrome c, RNase A, and high salt on MAC indicate that size, rather than charge, is crucial. The effects of dextran molecules of various sizes indicate that the pore diameter of MAC is slightly larger than that of 17-kDa dextran, which should be sufficient to allow the passage of 12-kDa cytochrome c. These findings are consistent with the notion that MAC is the pore through which cytochrome c is released from mitochondria during apoptosis.

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Section: Discussionmentioning

confidence: 94%

Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC

Guo

Pietkiewicz

Pavlov³

et al. 2004

American Journal of Physiology-Cell Physiology

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“…According to recent three-dimensional (3D) models of mitochondria derived from tomography imaging, the topology of the inner membrane defines domains of variable size, communicating with the intermembrane space through pores called "cristae junctions" of 14 nm inner diameter (55). Although the cytochrome c molecule is smaller than these pores [approximately 3 nm in diameter (56)], this has led to the hypothesis that the cristae might define local domains that limit diffusion.…”

Section: Discussionmentioning

confidence: 99%

Questioning the functional relevance of mitochondrial supercomplexes by time-resolved analysis of the respiratory chain

Trouillard

Meunier

Rappaport

2011

Proc. Natl. Acad. Sci. U.S.A.

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Mitochondria are the powerhouses of eukaryotic cells as they feed metabolism with its major substrate. Oxidative-phosphorylation relies on the generation, by an electron/proton transfer chain, of an electrochemical transmembrane potential utilized to synthesize ATP. Although these fundamental principles are not a matter of debate, the emerging picture of the respiratory chain diverges from the linear and fluid scheme. Indeed, a growing number of pieces of evidence point to membrane compartments that possibly restrict the diffusion of electron carriers, and to supramolecular assembly of various complexes within various kinds of supercomplexes that modulate the thermodynamic and kinetic properties of the components of the chain. Here, we describe a method that allows the unprecedented time-resolved study of the respiratory chain in intact cells that is aimed at assessing these hypotheses. We show that, in yeast, cytochrome c is not trapped within supercomplexes and encounters no particular restriction to its diffusion which questions the functional relevance of these supramolecular edifices.bioenergetics | electon transfer | respiration | compartmentalization

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“…The polymer exclusion method indicates that MAC with conductances between 1.5 and 5 nS have pore sizes of 2.9-7.6 nm, which should be large enough to allow the passage of B3 nm cytochrome c. 36 Is MAC the Cytochrome c Release Channel?…”

Section: Electrophysiological Characterization Of Macmentioning

confidence: 99%

“…45,46 However, oligomerization of Bax before insertion into planar bilayers allows for the formation of nonselective, voltage-independent channels that show a gradual increase in conductance up to 5.4 nS. 52 The diameter estimated from the peak conductance of 5.4 nS for Bax channels is 5.5 nm, which should easily allow the passage of B3 nm cytochrome c. 36 This discovery was recently confirmed in a study in which the channelforming activity of oligomeric Bax was monitored by patch-clamp techniques (see Table 1). 24 Like MAC, cytochrome c and RNAse A induce Type 1 and Type 2 effects in recombinant BaxDC20 channels, while hemoglobin has no effect (see current traces and histograms of Figure 3).…”

Section: Channel-forming Properties Of Bcl-2 Family Proteinsmentioning

confidence: 99%

Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis?

2006

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Apoptosis is a phenomenon fundamental to higher eukaryotes and essential to mechanisms controlling tissue homeostasis. Bcl-2 family proteins tightly control this cell death program by regulating the permeabilization of the mitochondrial outer membrane and, hence, the release of cytochrome c and other proapoptotic factors. Mitochondrial apoptosisinduced channel (MAC) is the mitochondrial apoptosisinduced channel and is responsible for cytochrome c release early in apoptosis. MAC activity is detected by patch clamping mitochondria at the time of cytochrome c release. The Bcl-2 family proteins regulate apoptosis by controlling the formation of MAC. Depending on cell type and apoptotic inducer, Bax and/or Bak are structural component(s) of MAC. Overexpression of the antiapoptotic protein Bcl-2 eliminates MAC activity. The focus of this review is a biophysical characterization of MAC activity and its regulation by Bcl-2 family proteins, and ends with some discussion of therapeutic targets.

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Primary Structure of the Cytochrome c from the Snapping Turtle, Chelydra Serpentina^*

Cited by 34 publications

References 35 publications

Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC

Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC

Questioning the functional relevance of mitochondrial supercomplexes by time-resolved analysis of the respiratory chain

Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis?

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Primary Structure of the Cytochrome c from the Snapping Turtle, Chelydra Serpentina*

Cited by 34 publications

References 35 publications

Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC

Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC

Questioning the functional relevance of mitochondrial supercomplexes by time-resolved analysis of the respiratory chain

Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis?

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Product

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Primary Structure of the Cytochrome c from the Snapping Turtle, Chelydra Serpentina^*