2ybb
From Proteopedia
Fitted model for bovine mitochondrial supercomplex I1III2IV1 by single particle cryo-EM (EMD-1876)
Structural highlights
FunctionNQO1_THET8 NDH-1 shuttles electrons from NADH, via FMN and iron-sulfur (Fe-S) centers, to quinones in the respiratory chain. The immediate electron acceptor for the enzyme in this species is menaquinone. Couples the redox reaction to proton translocation (for every two electrons transferred, four hydrogen ions are translocated across the cytoplasmic membrane), and thus conserves the redox energy in a proton gradient required for the synthesis of ATP. The nqo1 subunit contains the NADH-binding site and the primary electron acceptor FMN. Publication Abstract from PubMedThe respiratory chain in the inner mitochondrial membrane contains three large multi-enzyme complexes that together establish the proton gradient for ATP synthesis, and assemble into a supercomplex. A 19-A 3D map of the 1.7-MDa amphipol-solubilized supercomplex I(1)III(2)IV(1) from bovine heart obtained by single-particle electron cryo-microscopy reveals an amphipol belt replacing the membrane lipid bilayer. A precise fit of the X-ray structures of complex I, the complex III dimer, and monomeric complex IV indicates distances of 13 nm between the ubiquinol-binding sites of complexes I and III, and of 10-11 nm between the cytochrome c binding sites of complexes III and IV. The arrangement of respiratory chain complexes suggests two possible pathways for efficient electron transfer through the supercomplex, of which the shorter branch through the complex III monomer proximal to complex I may be preferred. Arrangement of electron transport chain components in bovine mitochondrial supercomplex I(1)III(2)IV(1).,Althoff T, Mills DJ, Popot JL, Kuhlbrandt W EMBO J. 2011 Sep 9. doi: 10.1038/emboj.2011.324. PMID:21909073[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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