CLONING AND CHARACTERIZATION OF A SPECIFIC INTERLEUKIN (IL)-13 BINDING-PROTEIN STRUCTURALLY RELATED TO THE IL-5 RECEPTOR-ALPHA CHAIN

Interleukin-13 (IL-13) is a cytokine secreted by activated T lymphocyt es that shares many, but not all, biological activities with IL-4. The se overlapping activities are probably due to the existence of common receptor components, Two proteins have been described as constituents of the IL-4 receptor, a similar to 140-kDa glycoprotein (IL-4R) and th e gamma chain (gamma c) of the IL-2 receptor, but neither of these pro teins binds IL-13, We have cloned a cDNA encoding an IL-13 binding pro tein (IL-13R) from the Caki-1 human renal carcinoma cell line. The clo ned cDNA encodes a 380-amino acid protein with two consensus patterns characteristic of the hematopoietic cytokine receptor family and a sho rt cytoplasmic tail, The IL-13R shows homology with the IL-5 receptor, and to a lesser extent, with the prolactin receptor, COS-7 cells tran sfected with the IL-13R cDNA bind IL-13 with high affinity but do not bind IL-4, COS-7 cells co transfected with the cloned IL-13R cDNA and IL-CR cDNA resulted in the reconstitution of a small number of recepto rs that recognized both IL-4 and IL-13, Reverse transcription-polymera se chain reaction analysis detected the receptor transcript only in ce ll lines known to bind IL-13.