Interleukin-21 receptor

Interleukin-21 receptor (IL-21R) is a type I cytokine receptor that is involved in the immune response. It is also known as CD360 (cluster of differentiation 360). The IL-21R is expressed on the surface of certain immune cells, including T cells, B cells, and natural killer (NK) cells. It binds to interleukin-21 (IL-21), a cytokine that plays a crucial role in both innate and adaptive immune responses.

Structure

The IL-21R is a type I cytokine receptor, which means it is a transmembrane protein with an extracellular domain that binds to cytokines, a transmembrane domain, and an intracellular domain that transmits signals into the cell. The extracellular domain of the IL-21R is composed of two fibronectin type-III domains, which are common structural motifs in cytokine receptors.

Function

When IL-21 binds to the IL-21R, it triggers a cascade of intracellular signaling events that ultimately lead to the activation of the immune cell. This can result in a variety of responses, depending on the type of cell. For example, in T cells, IL-21/IL-21R signaling can promote cell proliferation and the production of interferon-gamma (IFN-γ), a cytokine that has potent antiviral and immunoregulatory properties. In B cells, IL-21/IL-21R signaling can stimulate the production of antibodies.

Clinical significance

Abnormalities in the IL-21/IL-21R signaling pathway have been implicated in a number of diseases, including autoimmune diseases, inflammatory diseases, and cancers. For example, mutations in the IL-21R gene have been associated with the development of lupus, a chronic autoimmune disease. In addition, overexpression of the IL-21R has been observed in certain types of cancer, such as B-cell lymphoma.

See also

• Interleukin-21
• Cytokine receptor
• Immune system