Characterization of the human SDHD gene encoding the small subunit of cytochrome b (cybS) in mitochondrial succinate-ubiquinone oxidoreductase

We have mapped large (cybL) and small (cybS) subunits of cytochrome b in th e succinate-ubiquinone oxidoreductase (complex II) of human mitochondria to chromosome 1q21 and 11q23, respectively (H. Hirawake et al., Cytogenet. Ce ll Genet. 79 (1997) 132-138). In the present study, the human SDHD gene enc oding cybS was cloned and characterized. The gene comprises four exons and three introns extending over 19 kb. Sequence analysis of the 5' promoter re gion showed several motifs for the binding of transcription factors includi ng nuclear respiratory factors NRF-1 and NRF-2 at positions -137 and -104, respectively. In addition to this gene, six pseudogenes of cybS were isolat ed and mapped on the chromosome. (C) 1999 Elsevier Science B.V. All rights reserved.