Interleukin-2 (IL-2) binds to two distinct receptor molecules, the IL-2 receptor α (IL-2Rα, p55) chain and the newly identified IL-2 receptor β (IL-2Rβ, p70-75) chain. The cDNA encoding the human IL-2Rβ chain has now been isolated. The overall primary structure of the IL-2Rβ chain shows no apparent homology to other known receptors. Unlike the IL-2Rα chain, the IL-2Rβ chain has a large cytoplasmic region in which a functional domain (or domains) mediating an intracellular signal transduction pathway (or pathways) may be embodied. The cDNA-encoded β chain binds and internalizes IL-2 when expressed on T lymphoid cells but not fibroblast cells. Furthermore, the cDNA gives rise to the generation of high-affinity IL-2 receptor when co-expressed with the IL-2Rα chain cDNA.

Interleukin-2 Receptor β Chain Gene: Generation of Three Receptor Forms by Cloned Human α and β Chain cDNA's