Cytoplasmic cellular structures control permeability of outer mitochondrial membrane for ADP and oxidative phosphorylation in rat liver cells - PubMed (original) (raw)

. 1995 Aug 4;213(1):138-46.

doi: 10.1006/bbrc.1995.2108.

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Cytoplasmic cellular structures control permeability of outer mitochondrial membrane for ADP and oxidative phosphorylation in rat liver cells

E M Fontaine et al. Biochem Biophys Res Commun. 1995.

Abstract

The kinetics of regulation mitochondrial respiration by external ADP in permeabilized hepatocytes was studied further. In digitonin-permeabilized hepatocytes, the apparent Km for ADP in regulation of respiration was decreased from 275 +/- 35 microM in control to 48 +/- 8 microM by a treatment with trypsin (15 min, 0.125 mg/ml). In liver tissue homogenates, trypsin treatment similarly decreased the Km value for ADP. These results show that ADP diffusion in hepatocytes may be retarded due to some unknown cytoplasmic trypsin-sensitive protein factor(s) which may be lost during isolation of mitochondria. Since we have previously reported a limited permeability of the outer mitochondrial membrane in isolated hepatocytes (Saks et al. 1995, Biochem. Biophys. Res. Commun., 208, 919-926), we conclude that an important site of control of respiration in liver cells in vivo is located at the porin channels of the outer mitochondrial membrane.

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