Cloning and 5'-flanking sequence of a rat cholesterol 7 alpha-hydroxylase gene

A cholesterol 7 alpha-hydroxylase gene containing 8 kb of the 5'-flanking region and 5 kb of the transcription region which covers exons 1 to 5 was isolated from a rat genomic library. The 2015 bp nucleotide sequence 5'-upstream from the start codon was determined. This promotor region contains many liver-enriched or -specific elements (TGT3, HNF/LF-B1), putative hormone responsive elements (TRE, GRE, RRE or RARE) and ubiquitous transcription factor binding sites (NF-1, OCT-1). In addition, 21 CA repeats which have potential to form the Z-DNA structure were found in this region. These putative regulatory elements and repetitive motifs may play roles in the regulation of cholesterol 7 alpha-hydroxylase gene in the liver. The sequence identity of the rat gene to the human gene in this region is low. Only liver-enriched elements are conserved in the cholesterol 7 alpha-hydroxylase genes.