Human IL-2RB, also known asinterleukin-2 receptor subunit beta,is the receptor for interleukin-2. IL2 receptor complex is involved in receptor mediated endocytosis and transduces the mitogenic signals of IL2. IL2 receptor complex has three forms with respect to ability to bind IL2. IL-2RB is belonged to a type I membrane protein,and has a 26 residue signal peptide, a 214 residue extracellular region, a 25 residue transmembrane region and a 286 residue cytoplasmic domain. IL-2RB is the subunit critical for receptor-mediated signaling via physically or functionally coupling to other signaling molecules, such as the Jak-STAT and Src-family protein tyrosine kinase although it lacks apparent catalytic motifs.