IL-15 and IL-2 are two structurally and functionally related cytokines whose high affinity receptors share the IL-2R beta-chain and gamma-chain in association with IL-15R alpha-chain (IL-15R alpha) or IL-2R alpha-chain, respectively (Mortier et al 2004)
. The 2.8 angstrom crystal structure of IL-2 with the IL2RA was resolved by (Rickert et al. 2005)
. It revealed that the binding of IL-2R to IL-2 stabilizes a secondary binding site for presentation to IL-2R-beta. Gamma-c is then recruited to the composite surface formed by the IL-2/IL-2R-beta complex.