Authors: Tanaka, M; Miyabayashi, S; Nishikimi, M; Suzuki, H; Shimomura, Y; Ito, K; Narisawa, K; Tada, K; Ozawa, T
Abstract: This study was undertaken to estimate the extent of molecular defects in the mitochondrial electron-transfer chain of a patient with mitochondrial myopathy. Biochemical and immunochemical studies were performed on the skeletal muscle mitochondria. Spectrophotometry and enzyme activity measurements localized a definite defect at the segment of cytochrome c oxidase (complex IV) of the electron-transfer chain. Immunoblotting and immunoprecipitation studies using the anti-complex IV antibody revealed that the contents of subunits 1, 4, 5, 6, and 7 of complex IV were markedly diminished and that subunit 2 was almost absent. Immunohistochemistry of the muscle tissue revealed a considerable accumulation of immunoreactive materials of complex IV in the ragged-red fibers. The immunoblots using the anti-NADH-ubiquinone oxidoreductase antibody demonstrated that the contents of NADH-ubiquinone oxidoreductase subunits were 47% of control and that the contents of three subunits were considerably decreased. The contents of ubiquinol-cytochrome c oxidoreductase subunits were also somewhat low (77% of control) and one of the minor contaminants detected in the control was completely absent. High-resolution one-dimensional sodium dodecyl sulfate-urea-gel electrophoresis disclosed that six additional unidentified polypeptides in the control were markedly diminished or completely missing. These results demonstrate that the molecular defects in the mitochondrial electron-transfer chain are more extensive than would be expected from either spectral analysis or enzyme activity measurements alone, and involve not only complex IV but also NADH-ubiquinone oxidoreductase and ubiquinol-cytochrome c oxidoreductase and several unidentified mitochondrial proteins.
Keywords: Adult; Child; *Cytochrome-c Oxidase Deficiency; Electron Transport; Electron Transport Complex III/deficiency; Electrophoresis, Polyacrylamide Gel; Histocytochemistry; Humans; Immunoenzyme Techniques; Immunosorbent Techniques; Male; Mitochondria, Muscle/*enzymology/pathology; Muscles/*enzymology/pathology; Muscular Diseases/*etiology/pathology; NAD(P)H Dehydrogenase (Quinone); Quinone Reductases/deficiency|
Journal: Pediatr Res Volume: 24 Issue: 4 Pages: 447-54 Date: Oct. 1, 1988 PMID: 2845344 |
Tanaka, M, Miyabayashi, S, Nishikimi, M, Suzuki, H, Shimomura, Y, Ito, K, Narisawa, K, Tada, K, Ozawa, T (1988) Extensive defects of mitochondrial electron-transfer chain in muscular cytochrome c oxidase deficiency. Pediatr Res 24: 447-54.
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