IL2RG, also known as Interleukin-2 receptor common subunit gamma, is a cytokine receptor sub-unit that is common to the receptor complexes for at least six different interleukin receptors. This protein is located on the surface of immature blood-forming cells in bone marrow. One end of the protein resides outside of the cell where it binds to cytokines and the other end of the protein resides in the interior of the cell where it transmits signals to the cell's nucleus. The common gamma chain partners with other proteins to direct blood-forming cells to form lymphocytes. It also directs the growth and maturation of lymphocyte subtypes. These cells kill viruses, make antibodies, and help regulate the entire immune system.