Molecular cloning and characterization of the human AE2 anion exchanger (SLC4A2) gene

The human AE2 gene (HGMW-approved symbol SLC4A2) encompasses over 17 kb and contains 23 exons intervened by 22 introns. The size range for the exons is 90-255 bp, whereas that for the introns is 80 bp to 2.2 kb. Exon 1 consists solely of 5'-untranslated sequence, and exon 2 encodes the amino-terminal end of the antiport protein. Primer extension experiments suggest that there are multiple transcription initiation sites in leukocytes. The putative promoter region of the human AE2 gene contains no obvious TATA or CCAAT elements in the expected positions but has GC boxes, proposed sites for binding Sp1 transcription factor. These features, as well as the presence of several consensus elements such as GATA, LBP-1, E-box, CACC box, and T-antigen motif, indicate that the human AE2 promoter resembles the erythroid promoter of the human AE1 gene. The human AE2 gene (which has been previously mapped to chromosome 7) has three more introns than the human AE1 gene (mapped to chromosome 17), but downstream of intron 7 in the AE2 gene (corresponding to intron 4 in the AE1 gene), these two genes show a rather similar exon/intron organization.