STRUCTURAL COMPARISON AND CHROMOSOMAL LOCALIZATION OF THE HUMAN AND MOUSE IL-13 GENES

The genomic structure of the recently described cytokine IL-13 has bee n determined for both human and mouse genes. The nucleotide sequence o f a 4.6-kb DNA segment of the human gene is described. The human IL-13 gene (IL13) occurs as a single copy in the haploid genome and maps to human chromosome 5. A 4.3-kb DNA fragment of the mouse IL-13 gene (Il 13) has been sequenced and found to occur as a single copy, mapping to mouse chromosome 11. Intrachromosomal mapping studies revealed that b oth genes contain four exons and three introns and show a high degree of sequence identity throughout their length. Potential recognition se quences for transcription factors that are present in the 5'-flanking region and are conserved between both genes include IFN-responsive ele ments, binding sites for AP-1, AP-2 and AP-3, an NF-IL 6 site, and a T ATA-like sequence. Both genes map to chromosomal locations adjacent to genes encoding other cytokines, including IL-3, GM-CSF, IL-5, and IL- 4, suggesting that IL-13 is another member of this cytokine gene famil y that may have arisen by gene duplication.