Structure and analysis of the 5' flanking region of the human interleukin-2 gene.

To investigate the structural and functional organization of the human interleukin-2 locus, the nucleotide sequence of 9339 bp of the 5' flanking region of this gene has been determined. Computer search analysis reveals five stretches with a high degree of homology between the human and mouse 5' flanking sequence, including a very distant 5' region. In this region additional binding sites for potential transcription factors were found that are identical to known regulatory sequences. The possible roles of these putative regulatory elements in the interleukin-2 gene regulation remain to be proven. The 5' end of the sequence contains almost full-length LINE element. LINE consensus open reading frames ORF1 and ORF2 in the reported sequence are interrupted by insertions, deletions or in-frame nonsense mutations. Comparative analysis of the ratio of codon changes that result in amino acid replacement to those that are silent revealed a high silent mutation frequency throughout the consensus ORF1 3' end, suggesting that this region is probably under selection for protein function.