Interleukin-21 receptor–common gamma-chain complex (IL-21R–γc complex)

The **Interleukin-21 receptor–common gamma-chain complex** is a high-affinity heterodimeric cell surface receptor comprised of the private interleukin-21 receptor (IL-21R) and the common gamma chain (γc, also called IL2RG)[1][3][4][8]. This complex is essential for IL-21-mediated signal transduction in both innate and adaptive immune cells. Upon binding of IL-21, the receptor activates downstream pathways primarily via JAK1 and JAK3 tyrosine kinases, leading to phosphorylation of STAT1, STAT3, and sometimes STAT5 or STAT4, depending on cell type[4][6][8]. The common gamma chain is also shared with other cytokine receptors such as IL-2, IL-4, IL-7, IL-9, and IL-15, underlining its central role in immunological signaling[1][7][8]. Dysregulation of IL-21 signaling via this complex is implicated in numerous pathological states, including cancer, immune dysregulation, inflammation, and cardiovascular disease, and makes it an important therapeutic target in immune modulation[2][4][6].

Other names

Interleukin-21 receptor complexIL-21R–IL2RG complexIL-21 receptor / common γ-chain complexIL-21R–γc heterodimer

Antagonistic antibodies block IL-21 binding, preventing downstream signaling[1][7]. JAK inhibitors suppress receptor-mediated activation of JAK-STAT pathways[7][8].