title: NADH: ubiquinone oxidoreductase from bovine heart mitochondria. A fourth nuclear encoded subunit with a homologue encoded in chloroplast genomes.
abstract: The amino acid sequence has been determined of the precursor of a nuclear encoded 20 kDa subunit of complex I from bovine heart mitochondria. The sequence of the mature protein is related to a protein of uncertain function, hitherto known as psbG, encoded in the chloroplast genomes of higher plants. Open reading frames encoding homologues of psbG have also been detected in bacteria and in the mitochondrial genome of Paramecium tetraurelia. The chloroplast psbG gene is found between ndhC and ndhJ, which encode homologues of ND3, a hydrophobic subunit of complex I encoded in the bovine mitochondrial genome, and of the nuclear encoded 30 kDa subunit of complex I. This 20 kDa protein is the eleventh out of the forty or more subunits of bovine complex I with a chloroplast encoded homologue, and its sequence provides further support for the presence in chloroplasts of a multisubunit enzyme related to complex I that could be involved in chlororespiration. The strict conservation of three cysteines suggests that the subunit might be an iron-sulphur protein.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Arizmendi
authors.forename: M J
authors.initials: MJ
authors.lastname: Runswick
authors.forename: J M
authors.initials: JM
authors.lastname: Skehel
authors.forename: J E
authors.initials: JE
authors.lastname: Walker
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002736:Chloroplasts; D004247:DNA / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D008929:Mitochondria, Heart / Q000201:enzymology*; D008969:Molecular Sequence Data; D005810:Multigene Family; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics* / Q000378:metabolism; D016366:Open Reading Frames; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000596:Amino Acids; D004247:DNA; D016660:NAD(P)H Dehydrogenase (Quinone)