Cloning and structure of the human adrenodoxin gene

Adrenodoxin is an iron-sulfur protein that serves as an electron transport intermediate for all mitochondrial forms of cytochrome P450. To facilitate studying the regulation of adrenodoxin, we have cloned and determined the structure of the human adrenodoxin gene. It spans more than 20 kb, containing four exons and three introns. The first exon encodes the 60-amino-acid signal peptide, directing transport of the protein into the inner mitochondrial matrix. The mature peptide of 124 amino acids is encoded by the other three exons. The third exon encodes the portion of the protein containing the iron-sulfur center and a domain which binds other components of the electron transport chain. The transcriptional start sites were determined by primer extension and S1 nuclease mapping. The 5'-flanking region of this gene contains canonical promoters including a TATA box at nucleotide position -30 and two GC boxes at nucleotide positions -60 and -100. The sequence at nucleotides -234 to -252 is also highly homologous to the glucocorticoid-responsive element and the estrogen-responsive element.