Solution structure of human IL-13 and implication for receptor binding

Interleukin-13 has been implicated as a key factor in asthma, allergy, atopy and inflammatory response, establishing the protein as a valuable therapeutic target. The high-resolution solution structure of human IL-13 has been determined by multidimensional NMR. The resulting structure is consistent with previous short-chain left-handed four-helix bundles, where a significant similarity in the folding topology between IL-13 and IL-4 was observed. IL-13 shares a significant overlap in biological function with IL-4, a result of the common a chain component (IL-4R alpha) in their respective receptors. Based on the available structural and mutational data, an IL-13/IL-4R alpha model and a sequential mechanism for forming the signaling heterodimer is proposed for IL-13. (C) 2001 Academic Press.