title: Cytochrome oxidase: structural insights from electron microscopy and from secondary structure prediction.
abstract: Electron microscopic images of selectively contrasted cytochrome oxidase dimer crystals are interpreted in a manner consistent with the structure of monomers determined by Fuller et al. (J. Molec. Biol. 134, 305-327). The arms of the y-shaped monomers lie within and perpendicular to the lipid bilayer protruding approximately 25 A on the matrix side of the membrane. The cytoplasmic-side tails of two monomers spread apart in a dimer forming a large cleft. Decoration of the exposed matrix side of vesicle crystals with antisubunit IV antibody fragments indicates that subunit IV lies along the a-crystal axis roughly 20 A from the center of the dimer. A membrane propensity algorithm applied to the sequences of cytochrome oxidase subunits predicts a total of 19 transmembrane alpha-helices per monomer.
authors.forename: T G
authors.initials: TG
authors.lastname: Frey
authors.forename: L A
authors.initials: LA
authors.lastname: Kuhn
authors.forename: J S
authors.initials: JS
authors.lastname: Leigh
authors.forename: M J
authors.initials: MJ
authors.lastname: Costello
authors.forename: S H
authors.initials: SH
authors.lastname: Chan
mesh_terms: D001666:Binding Sites, Antibody; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D003576:Electron Transport Complex IV; D005612:Freeze Drying; D005614:Freeze Fracturing; D007140:Immunoglobulin Fab Fragments; D007158:Immunologic Techniques; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008565:Membrane Proteins; D008854:Microscopy, Electron; D011487:Protein Conformation
chemical_list: D007140:Immunoglobulin Fab Fragments; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008565:Membrane Proteins; D003576:Electron Transport Complex IV