Interleukin 21 receptor is a

type I cytokine receptor Type I cytokine receptors are transmembrane receptors expressed on the surface of cells that recognize and respond to cytokines with four α-helical strands. These receptors are also known under the name ''hemopoietin receptors'', and share a c ...

. IL21R is its human

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

. The protein encoded by this gene is a cytokine receptor for

interleukin 21 Interleukin 21 (IL-21) is a protein that in humans is encoded by the ''IL21'' gene. Interleukin-21 is a cytokine that has potent regulatory effects on cells of the immune system, including natural killer (NK) cells and cytotoxic T cells that can ...

(IL21). It belongs to the type I cytokine receptors, and has been shown to form a heterodimeric receptor complex with the common gamma chain (γc), a receptor subunit also shared by the receptors for interleukin 2 (IL2), interleukin 7 (IL7) and interleukin 15 (IL15). This receptor transduces the growth promoting signal of IL21, and is important for the proliferation and differentiation of T cells, B cells, and natural killer (NK) cells. The ligand binding of this receptor leads to the activation of multiple downstream signaling molecules, including JAK1, JAK3, STAT1, and STAT3. Knockout studies of a similar gene in mouse suggest a role for this gene in regulating immunoglobulin production. Three alternatively spliced transcript variants encoding the same protein have been described.

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