Interleukin-2 receptor

Interleukin-2 receptor (IL-2R) is a type of protein that is found on the surface of certain immune cells. It plays a crucial role in the immune response by binding to interleukin-2 (IL-2), a type of cytokine that stimulates the growth and differentiation of T cells, B cells, and natural killer cells.

Structure

The IL-2R is composed of three different subunits: alpha (CD25), beta (CD122), and gamma (CD132). The alpha subunit is specific to the IL-2R, while the beta and gamma subunits are shared with other cytokine receptors. The binding of IL-2 to the alpha subunit increases the affinity of the receptor for IL-2, allowing it to bind more effectively.

Function

The primary function of the IL-2R is to bind to IL-2 and initiate a signal cascade that leads to the activation of immune cells. This is achieved through the JAK-STAT signaling pathway, which is initiated when IL-2 binds to the IL-2R. This binding causes the receptor to undergo a conformational change, which allows it to activate the Janus kinase (JAK) proteins that are associated with it. These proteins then phosphorylate and activate the Signal transducer and activator of transcription (STAT) proteins, which translocate to the nucleus and initiate the transcription of genes that are involved in cell growth and differentiation.

Clinical significance

Abnormalities in the IL-2R can lead to a variety of immune disorders. For example, mutations in the genes that encode the IL-2R can cause severe combined immunodeficiency (SCID), a condition that is characterized by a severe impairment of the immune system. Additionally, elevated levels of soluble IL-2R have been associated with certain types of cancer, including Hodgkin's lymphoma and non-Hodgkin's lymphoma, and autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus.

See also

• Interleukin-2
• Cytokine receptor
• Immune response
• JAK-STAT signaling pathway

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