The Interleukin 2 Receptor alpha and beta chains, along with the common gamma chain, comprise the high affinity IL2 receptor(IL2R) that is present on both mature activated T- and B-cells, as well as early progenitors of T- and B-cells (thymocytes, pre B-cells, and T-regulatory cells). Formation of homodimeric alpha chains (IL2RA) results in a low affinity receptor, while homodimeric beta chains (IL2RB) produce a medium affinity receptor. IL2RA is normally an integral membrane protein, but a soluble IL2 Receptor alpha has been isolated and appears as the result of extracellular proteolysis.
