The protein encoded by this gene is a cytokine receptor for interleukin 21 (IL21). It belongs to the type I cytokine receptors, and has been shown to form a heterodimeric receptor complex with the common gamma-chain, 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.[5]
Parrish-Novak J; Dillon SR; Nelson A; et al. (2000). "Interleukin 21 and its receptor are involved in NK cell expansion and regulation of lymphocyte function". Nature. 408 (6808): 57–63. doi:10.1038/35040504. PMID11081504. {{cite journal}}: Unknown parameter |name-list-format= ignored (|name-list-style= suggested) (help)
Jüngel A; Distler JH; Kurowska-Stolarska M; et al. (2004). "Expression of interleukin-21 receptor, but not interleukin-21, in synovial fibroblasts and synovial macrophages of patients with rheumatoid arthritis". Arthritis Rheum. 50 (5): 1468–1476. doi:10.1002/art.20218. PMID15146416. {{cite journal}}: Unknown parameter |name-list-format= ignored (|name-list-style= suggested) (help)
Li J, Shen W, Kong K, Liu Z (2006). "Interleukin-21 induces T-cell activation and proinflammatory cytokine secretion in rheumatoid arthritis". Scand. J. Immunol. 64 (5): 515–522. doi:10.1111/j.1365-3083.2006.01795.x. PMID17032244.
Asano K; Ikegami H; Fujisawa T; et al. (2007). "Molecular scanning of interleukin-21 gene and genetic susceptibility to type 1 diabetes". Hum. Immunol. 68 (5): 384–391. doi:10.1016/j.humimm.2007.01.009. PMID17462506. {{cite journal}}: Unknown parameter |name-list-format= ignored (|name-list-style= suggested) (help)
Akamatsu N; Yamada Y; Hasegawa H; et al. (2007). "High IL-21 receptor expression and apoptosis induction by IL-21 in follicular lymphoma". Cancer Lett. 256 (2): 196–206. doi:10.1016/j.canlet.2007.06.001. PMID17624663. {{cite journal}}: Unknown parameter |name-list-format= ignored (|name-list-style= suggested) (help)