The γc glycoprotein is a member of the type I cytokine receptor family expressed on most lymphocyte (white blood cell) populations, and its gene is found on the X-chromosome of mammals.

Lymphocytes expressing the common gamma chain can form functional receptors for these cytokine proteins, which transmit signals from one cell to another and direct programs of cellular differentiation.

The γc chain partners with other ligand-specific receptors to direct lymphocytes to respond to cytokines including IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21.

Once either IL4-Rα, IL-7Rα, IL-9Rα, IL-21Rα, IL-2R or IL-15R has bound to their respective ligands, IL2RG is quickly recruited and forms a heterodimer with the cytoplasmic tail of the opposing receptor.

A lack of functional mature lymphocytes disrupts the immune system's ability to protect the body from infection.

Affected people have no functional immunity and can die within months after birth without successful bone marrow transplantation or alternatively, isolation from exposure to pathogens.