The gene for the human interleukin-11 receptor alpha chain locus is highly homologous to the murine gene and contains alternatively spliced first exons

The gene for the murine interleukin-11 receptor α chain (mIL-11Rα) contains two loci (1 and 2), of which locus 2 is restricted to only some mouse strains. Two alternatively spliced exons (1a and 1b) encode the 5′ untranslated region (5′UTR) of the murine locus 1. We have characterized the gene for the human interleukin-11 receptor α chain locus (hIL-11Rα), examined its expression by Northern analysis and determined its chromosomal location by fluorescence in situ hybridization. The presence of exon(s) encoding the 5′UTR and mapping of transcription initiation sites was determined by reverse-transcriptase polymerase chain reaction and 5′ rapid amplification of cDNA ends (5′RACE) techniques. The human locus spanned 10 kilobasepairs (kb) and consisted of 14 exons. Two alternatively spliced first exons (1a and 1b) encoding the 5′UTR were identified and shared 76 and 73% nucleotide identity with murine exons 1a and 1b. Multiple transcription start sites were demonstrated for human exon 1a. The promoter regions of both human exons 1a and 1b did not display a canonical TATA box. A predominant 1.8 kb transcript for the hIL-11Rα was present in heart, brain, skeletal muscle, lymph nodes, thymus, appendix, pancreas and foetal liver. The hIL-11Rα gene was localized to chromosome 9p13. In summary, the hIL-11Rα gene was highly related to locus 1 of the murine gene and there was no evidence of a second hIL-11Rα locus.