Interleukin-11 (IL-11) is a multifunctional cytokine involved in the regulation of cell proliferation and differentiation in a variety of cell types and tissues in vitro and in vivo. The effects of IL-11 were shown to be mediated by the IL-11 receptor (hereafter referred to as IL-11Rα), which is a ligand-binding subunit and provides ligand specificity in a functional multimeric signal-transduction complex with gp130. Here we show that the mouse genome contains a second gene encoding an IL-11-binding protein, referred to as IL-11Rβ. The structure of the IL-11Rβ gene is highly similar to that of IL-11Rα, and IL-11Rβ exhibits 99% sequence identity with IL-11Rα at the amino acid level. IL-11Rβ is co-expressed with IL-11Rα, albeit at lower levels, in embryos and in various adult tissues. IL-11Rβ transcripts are abundant in testis, and, in contrast with IL-11Rα, absent from skeletal muscle. IL-11Rβ expressed in vitro binds IL-11 with high affinity, suggesting that the mouse genome contains a second functional IL-11R.
Present address: MPI für Neurologische Forschung, Gleuelerstr. 50, 50829 Köln, Germany.
The nucleotide sequence data reported here have been deposited in the EMBL Nucleotide Sequence Database under the accession numbers X94162 and X94163 for the IL-11Rα gene, X94157–X94161 for the IL-11Rβ gene and X98519 for the IL-11Rβ cDNA.