title: Direct evidence for two distinct forms of the flavoprotein subunit of human mitochondrial complex II (succinate-ubiquinone reductase).
abstract: Succinate-ubiquinone reductase (complex II) is an important enzyme complex in both the tricarboxylic acid cycle and aerobic respiration. A recent study showed that defects in human complex II are associated with cancers as well as mitochondrial diseases. Mutations in the four subunits of human complex II are associated with a wide spectrum of clinical presentations. Such tissue-specific clinical symptoms suggest the presence of multiple isoforms of the subunits, but subunit isoforms have not been previously reported. In the present study, we identified two distinct cDNAs for the human flavoprotein subunit (Fp) from a single individual, and demonstrated expression of these two isoforms in skeletal muscle, liver, brain, heart and kidney. Interestingly, one of the Fp isoforms was encoded as an intronless gene.
authors.affiliation: Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033.
authors.forename: Eriko
authors.initials: E
authors.lastname: Tomitsuka
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hirawake
authors.forename: Yu-ichi
authors.initials: Y
authors.lastname: Goto
authors.forename: Masafumi
authors.initials: M
authors.lastname: Taniwaki
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Harada
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kita
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D042963:Electron Transport Complex II / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D005260:Female; D005420:Flavoproteins / Q000737:chemistry*; D006801:Humans; D007438:Introns / Q000235:genetics; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D005420:Flavoproteins; D007527:Isoenzymes; D021122:Protein Subunits; D011994:Recombinant Proteins; D042963:Electron Transport Complex II