Structural Analysis of the Gene Encoding the Murine Interleukin-11 Receptor α-Chain and a Related Locus*

In this study the gene for the murine interleukin-11 receptor α chain (IL-11Rα) has been characterized. The gene spans 9 kilobase pairs of DNA, and the organization of its 14 exons conforms to the pattern observed for other members of the hematopoietin receptor family. Analysis of the 5′ end of the cDNA using 5′ RACE showed that the first two exons, designated exons 1a and 1b, are spliced to form alternate transcripts. Transcripts initiating from exon 1b were not found in adult tissues but were present in embryonic stem cells. S1 nuclease and 5′ rapid amplification of cDNA ends assays demonstrated multiple major and minor sites of transcription initiation for each exon. The putative promoter regions of both exons lacked TATA boxes, although potential recognition sites for several transcription factors including Sp1, AP1, and AP2 were present. A comparison of the murine and human IL-11Rα revealed that the 5′ sequence upstream of the major site of transcription initiation site for exon 1b is highly conserved. Northern analysis showed that IL-11Rα is expressed in many adult murine tissues. A second IL-11Rα-like locus containing a sequence homologous to exons 2-13 was also identified.