Interleukin-2 receptor heterotrimeric complex (IL-2Rαβγ)

The Interleukin-2 receptor (IL-2R) heterotrimeric complex is a high-affinity signaling assembly composed of three distinct subunits: IL-2Rα (CD25), IL-2Rβ (CD122), and the common gamma chain (γc, CD132) (UniProt P01589, P14784, P31785). This complex is primarily expressed on activated T cells and regulatory T cells (Tregs), where it mediates the potent proliferative and survival signals of the cytokine IL-2 (Liao et al., 2013, Immunity). Upon IL-2 binding, the complex triggers the JAK/STAT, PI3K/Akt, and MAPK signaling pathways, which are essential for the expansion of effector T cells and the maintenance of immune tolerance via Tregs (Ross & Cantrell, 2018, Annual Review of Immunology). Because of its central role in the immune response, the heterotrimeric IL-2R is a major therapeutic target in both oncology and immunology (Malek, 2008, Annual Review of Immunology). Monoclonal antibodies like basiliximab block the alpha subunit to prevent transplant rejection, while IL-2 agonists are used in oncology to stimulate anti-tumor immunity (Waldmann, 2006, Nature Reviews Immunology). The high-affinity heterotrimeric form is distinguished from the low-affinity monomeric and intermediate-affinity dimeric forms by its significantly higher sensitivity to IL-2, allowing Tregs to signal even at low cytokine concentrations.

Other names

High-affinity IL-2 receptorCD25/CD122/CD132 complexIL-2R alpha/beta/gamma complexIL2RABCInterleukin-2 receptor alpha/beta/gamma

Competitive antagonism of the IL-2Rα subunit to inhibit T-cell activation; Agonism of the heterotrimeric complex to stimulate T-cell and NK-cell proliferation; Targeted delivery of cytotoxic moieties via IL-2R binding.