Common gamma chain

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The Cytokine receptor common gamma chain (γ_c) (or CD132) is a cytokine receptor sub-unit that is common to the receptor complexes for at least six different interleukin receptors: IL-2, IL-4, IL-7, IL-9, IL-15 and interleukin-21 receptor. The common γ_c 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.

Structure

Common γ_c is an integral membrane protein that spans across the cell membrane, with extracellular, transmembrane and cytosilic (inside the cell) domains.

Ligands

The common γ_c 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.

Function

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.

Gene

IL2RG is the gene that encodes the common gamma chain.

Clinical significance

Defects in the common γ_c are the major cause of X-linked severe combined immunodeficiency (X-SCID) in humans, sufferers have no functional immunity and die within months after birth without successful bone marrow transplantation or isolation from pathogens. Mutations that result in no common γ_c, or remove the signal transducing cytosilic domain result in this disorder. Without important developmental signals from IL-7 and IL-15, T-cell and NK cell populations respectively fail to develop. Experiments in animal models has shown X-SCID to occur similarly in dogs, but not in mice. Less disastrous defects in the common γ_c gene can result in X-linked combined immunodeficiency (X-CID), a less severe form of immunodeficiency.

References

External links

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Last updated on Monday June 09, 2008 at 16:26:54 PDT (GMT -0700)
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