STRUCTURAL DIFFERENCES IN 5'-FLANKING REGIONS OF RAT CYTOCHROME-P-450ALDO AND CYTOCHROME-P-45011-BETA GENES

Two rat genomic clones, one for cytochrome P-450aldo and the other for P45011β, were isolated and characterized. The two genes, encoding structurally homologous proteins, were closely similar in their intron-exon organizations. Their 5′-flanking regions, however, contained only a few homologous regions. A putative cyclic AMP responsive element, TGACGTGA, was found in the P-450aldo gene, but this sequence was altered at two positions in the P-45011β gene. S1 nuclease protection assay revealed a single transcription initiation site for the P450aldo gene, while multiple sites were found for the P-45011β gene. These results suggest that transcriptional regulation of the rat P-450aldo and P-45011β genes is due to differences in the sequences of their 5′-flanking regions. © 1991 Academic Press, Inc.