The human interleukin-2 receptor β-chain gene: genomic organization, promoter analysis and chromosomal assignment

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Abstract
The chromosomal gene for the human interleukin-2 receptor β-chain (IL-2Rβ) was isolated and characterized. The entire IL-2Rβ3 gene is composed of ten exons spanning about 24.3 kilobases, in which the protein is encoded by the exons 2–10. The cysteine rich extracellular region which displays a significant evolutionary resemblance to other cytokine receptors, as well as growth hormone and prolactin receptors, is encoded primarily by exons 3 and 4, whereas the membrane proximal, cysteine poor domain showing a homology with type III modules of fibronectin is encoded by exon 7. Sequence analysis of the 5'-flanking region revealed the presence of potential binding sites for transcription factors such as Octamer binding factors, AP-1, AP-2 as well as the ‘GC-clusters’. At least five potential cap sites were identified by S1 mapping analysis. The 850 bp DNA sequence of the 5'-flanking region exhibited constitutive promoter activity when it was linked upstream of the HSV-tk reporter gene and then transfected into YT cells, a human leukemic cell line. By applying the RFLP linkage analysis, the IL-2Rβ gene has been assigned to chromosome 22q12–13.