Ornithine/phosphate antiport in rat kidney mitochondria

In rat cerebellar granule cells, cytochrome c release takes place during glutamate toxicity and apoptosis due to deprivation of depolarising levels of potassium. We show that, as in necrosis, the released cytochrome c present in the cytosolic fraction obtained from cerebellar granule cells undergoing apoptosis can operate as a reactive oxygen species (ROS) scavenger and as a respiratory substrate. The capability of the cytosolic fraction containing cytochrome c, obtained from cerebellar granule cells undergoing either necrosis or apoptosis, to energise coupled mitochondria isolated by the same cells is also investigated. We show that, in both cases, the cytosolic fraction containing cytochrome c, added to mitochondria, can cause proton ejection, and membrane potential generation and can drive ATP synthesis and export in the extramitochondrial phase, as photometrically measured via the ATP detecting system. Cytochrome c, separated immunologically from the cytosolic fraction of apoptotic cells when added to mitochondria, is found to cause proton ejection to generate membrane potential and to drive ATP synthesis and export in a manner not sensitive to the further addition of the cytosolic fraction depleted of cytochrome c, which failed to do this. In the light of these findings we propose that in apoptosis the released cytochrome c can contribute to provide ATP required for the cell programmed death to occur.

show abstract

“…Proton movement across the mitochondrial membrane was followed, as previously reported (Passarella et al . 1990; de Bari et al .…”

Section: Proton Movement Measurementsmentioning

confidence: 85%

Cytochrome c, released from cerebellar granule cells undergoing apoptosis or excytotoxic death, can generate protonmotive force and drive ATP synthesis in isolated mitochondria

Atlante

Bari

Bobba

et al. 2003

Journal of Neurochemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…For example, differential expression of the arginase isoenzymes could provide a means to preferentially direct ornithine either to proline or glutamate synthesis via OAT or to polyamine synthesis via ODC (Figure 2). If so, this would imply that ornithine does not rapidly equilibrate between cytosolic and mitochondrial compartments, despite the existence of transporters via which ornithine can traverse the mitochondrial membrane [204][205][206][207][208]. So far as we are aware, no experiments to determine the effect of arginase localization on the metabolic fates of ornithine have been performed.…”

Section: Arginasementioning

confidence: 99%

Arginine metabolism: nitric oxide and beyond

Morris

1998

Biochemical Journal

2,425

2,036

View full text Add to dashboard Cite

Arginine is one of the most versatile amino acids in animal cells, serving as a precursor for the synthesis not only of proteins but also of nitric oxide, urea, polyamines, proline, glutamate, creatine and agmatine. Of the enzymes that catalyse rate-controlling steps in arginine synthesis and catabolism, argininosuccinate synthase, the two arginase isoenzymes, the three nitric oxide synthase isoenzymes and arginine decarboxylase have been recognized in recent years as key factors in regulating newly identified aspects of arginine metabolism. In particular, changes in the activities of argininosuccinate synthase, the arginases, the inducible isoenzyme of nitric oxide synthase and also cationic amino acid transporters play major roles in determining the metabolic fates of arginine in health and disease, and recent studies have identified

show abstract

“…Maleimides (N-ethylmaleimide and eosin 5-maleimide) and 5,5'-dithiobis(2-nitrobenzoate) also strongly inhibited the carrier activity, although less efficiently than the mercurials. PrC13, found to inhibit an ornithine/phosphate exchange in kidney mitochondria [9], inhibited the purified ornithine/ citrulline carrier but only at high concentrations. The data of Table 5 also show that the reconstituted ['4C]ornithine exchange was inhibited by externally added citrulline and lysine.…”

Section: Functional Characterization Of the Ornithine/citrulline Carriermentioning

confidence: 99%

“…Correspondence to F. Palmieri electrogenic ornithine/phosphate exchange has been shown to occur [9].…”

mentioning

confidence: 99%

Identification and purification of the ornithine/citrulline carrier from rat liver mitochondira

Indiveri

Tonazzi

Palmieri

1992

European Journal of Biochemistry

View full text Add to dashboard Cite

The ornithine/citrulline carrier from rat liver mitochondria, solubilized with Triton X-1 00 and partially purified on hydroxyapatite, was identified and completely purified by PD-10, DEAESephacel and celite chromatography. On SDS/polyacrylamide gel electrophoresis, the purified ornithine/citrulline carrier consisted of a single protein band with an apparent molecular mass of 33.5 kDa. When reconstituted into liposomes the ornithine carrier protein catalyzed an active mersalyl sensitive ornithine/ornithine exchange. It was purified 438-fold with a recovery of 38% and a protein yield of 0.09% with respect to the extract derived from mitoplasts. The purified and reconstituted protein did not catalyze a significant unidirectional transport of ornithine. Citrulline was found to be the best countersubstrate for the transport of ornithine, followed by lysine and arginine. The exchange activity was inhibited by several sulphydryl reagents.In liver, two enzymes of the urea cycle, ornithine transcarbamylase and carbamyl phosphate synthetase I, are located in the mitochondrial matrix, while the other enzymes are cytoplasmic. Thus, for the operation of the urea cycle, ornithine must pass from the cytosol to the mitochondrial matrix where it is carbamylated to citrulline, and citrulline must leave the mitochondria in order to regenerate ornithine.The presence of an ornithine/citrulline carrier in the inner mitochondrial membrane has already been predicted in 1972 from theoretical and metabolic considerations [l]. However, the experimental evidence supporting the existence of this carrier in intact mitochondria is only circumstantial and not as definitive as for other mitochondrial metabolite carriers (for a review see [2 and 31). Based on the osmotic swelling of rat liver mitochondria, Gamble and Lehninger [4] [7], using rat liver mitochondria loaded with citrulline, presented evidence for the existence of an ornithine/citrulline-exchange system. These authors observed the uptake of ornithine in citrulline-loaded mitochondria and citrulline efflux from these mitochondria upon addition of ornithine or lysine. In a subsequent study 181, no evidence could be obtained for an ornithine/citrulline or lysine/citrulline exchange, whereas it was concluded that ornithine and lysine are taken up by rat liver mitochondria in exchange for H'. Recently, in rat kidney mitochondria, an The final proof for the existence of a particular carrier protein is its isolation. So far, an ornithine-transport protein has only been reconstituted into liposomes from a Lubrol WX extract of rat liver mitochondria [lo]. In this paper, we describe the isolation and purification of the ornithine/citrulline carrier from rat liver mitochondria using functional reconstitution as a monitor of the carrier activity during the isolation procedure. MATERIALS AND METHODS MaterialsHydroxyapatite (Bio-Gel HTP) was purchased from BioRad, Celite 535 from Roth, Amberlite XAD-2 from Fluka, DEAE-Sephacel, Sephadex PD-10, Sephadex G-50 and Sephadex G-75 from Pharmacia, L-[ ...

show abstract

Ornithine/phosphate antiport in rat kidney mitochondria

Cited by 23 publications

References 32 publications

Cytochrome c, released from cerebellar granule cells undergoing apoptosis or excytotoxic death, can generate protonmotive force and drive ATP synthesis in isolated mitochondria

Cytochrome c, released from cerebellar granule cells undergoing apoptosis or excytotoxic death, can generate protonmotive force and drive ATP synthesis in isolated mitochondria

Arginine metabolism: nitric oxide and beyond

Identification and purification of the ornithine/citrulline carrier from rat liver mitochondira

Contact Info

Product

Resources

About