Characterization of a membrane fragment of respiratory chain complex I from Neurospora crassa. Insights on the topology of the ubiquinone-binding site.
1. A membrane fragment of complex I from the fungus Neurospora crassa was isolated by immunoprecipitation from alkaline-extracted mitochondrial membranes. 2. Analysis of the polypeptide composition of this hydrophobic domain of complex I has brought insights on the topology of two subunits of the enzyme, namely the 20.8 and 9.3 kDa components. 3. Our results indicate that the ubiquinone-binding site of complex I resides in the interface of the peripheral and membrane arms of the enzymes. The significance of these findings are discussed.
Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Portugal.
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Azevedo
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Videira
D001665:Binding Sites; D007425:Intracellular Membranes / Q000201:enzymology; D008928:Mitochondria / Q000201:enzymology; D008956:Models, Chemical; D008970:Molecular Weight; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D009492:Neurospora crassa / Q000201:enzymology*; D011487:Protein Conformation; D014451:Ubiquinone / Q000378:metabolism*
D014451:Ubiquinone; D016660:NAD(P)H Dehydrogenase (Quinone)