Saito Y, Honjo T
Department of Medical Chemistry, Kyoto University Faculty of Medicine, Japan.
Prog Growth Factor Res. 1990;2(4):207-22. doi: 10.1016/0955-2235(90)90019-g.
The interleukin 2 receptor (IL-2R) is composed of at least two proteins, that is, a 55 kDa L chain (p55, alpha chain) and a 75 kDa H chain (p75, beta chain). The high-affinity binding of IL-2 results in the formation of the ternary complex consisting of IL-2, the L chain and the H chain. Kinetic studies on the IL-2 binding to the high-affinity IL-2R have shown that the association of IL-2 to the L chain is the first step of the ternary complex formation and that expression of a larger number of L chains accelerates the association of IL-2 to the high-affinity IL-2R in agreement with the stepwise binding/affinity conversion model. This conclusion was supported by experiments using several monoclonal antibodies directed to either H or L chain and murine T cell lines which was transfected by the human L chain cDNA. Temperature-sensitive IL-2 binding to the high-affinity receptor is also consistent with the above conclusion. Signal transduction by the IL-2R appears to involve the activation of tyrosine protein kinase. IL-2 signal transduction seems to require the H chain and another yet unidentified molecule, which might have the kinase activity.
白细胞介素2受体（IL-2R）至少由两种蛋白质组成，即一条55 kDa的轻链（p55，α链）和一条75 kDa的重链（p75，β链）。IL-2的高亲和力结合导致由IL-2、轻链和重链组成的三元复合物的形成。对IL-2与高亲和力IL-2R结合的动力学研究表明，IL-2与轻链的结合是三元复合物形成的第一步，并且大量轻链的表达加速了IL-2与高亲和力IL-2R的结合，这与逐步结合/亲和力转换模型一致。使用几种针对重链或轻链的单克隆抗体以及转染了人轻链cDNA的小鼠T细胞系进行的实验支持了这一结论。对高亲和力受体的温度敏感性IL-2结合也与上述结论一致。IL-2R的信号转导似乎涉及酪氨酸蛋白激酶的激活。IL-2信号转导似乎需要重链和另一种尚未鉴定的分子，该分子可能具有激酶活性。
