J. Biochem, 2003, Vol. 134, No. 2 191-195
© 2003 Japanese Biochemical Society
BIOCHEMISTRY |
Direct Evidence for Two Distinct Forms of the Flavoprotein Subunit of Human Mitochondrial Complex II (Succinate-Ubiquinone Reductase)
1 Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033; 2 Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502; 3 Department of Clinical Molecular Genetics and Laboratory Medicine, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-0841; 4 Department of Structural Biology, Graduate School of Pharmaceutical Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033
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.
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