STRUCTURAL ORGANIZATION AND CHROMOSOMAL MAPPING OF JAK3 LOCUS

In this study, we have isolated the genomic DNA clone encoding the mur ine JAK3 gene and determined its sequence. Partial genomic clones of t he JAK1 and JAK2 genes encoding the tyrosine kinase domain were also i solated and compared with JAK3. The genomic structure of JAK3 consists of 23 exons. The exon/intron boundaries and the distribution of codin g sequences within the exons of each of the three JAK genes were found to follow a similar pattern suggesting that various members of the JA K family have originated from a single primordial gene by duplication and the structure has been closely maintained through evolution. Using in situ hybridization and FISH analysis, we have mapped the JAK3 gene to human chromosome 19p13.1-p13.2.