Comparison of the 5' regions of human and mouse carbonic anhydrase II genes and identification of possible regulatory elements.

The nucleotide sequence of the 5' region of the human carbonic anhydrase II gene has been determined. This sequence begins 643 base pairs upstream from the ATG start site and continues through exon 1, intron 1, exon 2 and the adjoining 125 nucleotides of intron 2. The human sequence is compared with homologous regions of the mouse (YBR strain) carbonic anhydrase II gene by aligning the two sequences for optimal homology. In addition to a TATA box and a putative CCAAT box (CCACC in human and CCACT in mouse), three conserved tandem-repeat elements in mouse and two in human (consensus: cCNGTCACCTCCgC) are located 15 and 22 base pairs upstream, respectively, from the CCAAT boxes in the human and mouse sequences. This repeat element is similar to a tandem repeat sequence located at about the same position in mammalian beta-globin genes, and may represent regulatory elements common to both the carbonic anhydrase and beta-globin genes. The regions surrounding exon 1 are extremely G + C-rich in both human and mouse genes. In addition, several CCGCCC or GGGCGG sequences which may be important for transcriptional efficiency are found in the 5' flanking regions of the human and mouse genes.