Interleukin-2 receptor (IL-2R) is a heterotrimeric protein expressed on the surface of certain immune cells, such as lymphocytes, that binds and responds to a cytokine called IL-2. The IL-2R is made up of 3 subunits - α (CD25), β (CD122) and γ (CD132) - non-covalently associating. The α and β chains are involved in binding IL-2, while signal transduction following cytokine interaction is carried out by the γ-chain, along with the β subunit. CD122 is also known as IL2R beta, is a member of the type I cytokine receptor family. CD122 is the receptor for interleukin-2 and is involved in receptor mediated endocytosis and transduces the mitogenic signals of IL2.