Baniyash M, Garcia-Morales P, Bonifacino J S, Samelson L E, Klausner R D
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
J Biol Chem. 1988 Jul 15;263(20):9874-8.
The T cell antigen receptor (TCR) is a multisubunit membrane complex. It consists of two disulfide-linked polymorphic chains (either alpha-beta or gamma-delta heterodimers) which are noncovalently linked to five invariant chains. The CD3-gamma and CD3-delta chains bear N-linked carbohydrates and the CD3-epsilon and zeta chains are nongly-cosylated. Further analysis of the zeta chain in murine T cells demonstrates that it can exist as either a homodimer or disulfide linked to an additional protein with an apparent Mr of 22,000. The partial peptide map of this 22-kDa protein is different than zeta and all of the CD3 components. Like zeta, it has no apparent N-linked carbohydrate chains. We have chosen to refer to this subunit as the eta chain of the TCR. Ninety percent of zeta in cloned and nonclonal populations of T cells exist as a homodimer, and the remainder is found linked to the eta chain. The tight regulation of the zeta-zeta to zeta-eta ratio suggests an important functional role for these structural components of the TCR.
T细胞抗原受体（TCR）是一种多亚基膜复合物。它由两条通过二硫键连接的多态性链（α-β或γ-δ异二聚体）组成，这些链与五条恒定链非共价连接。CD3-γ和CD3-δ链带有N-连接的碳水化合物，而CD3-ε和ζ链是非糖基化的。对小鼠T细胞中ζ链的进一步分析表明，它可以以同二聚体形式存在，也可以通过二硫键与另一种表观分子量为22,000的蛋白质连接。这种22-kDa蛋白质的部分肽图与ζ链和所有CD3成分不同。与ζ链一样，它没有明显的N-连接碳水化合物链。我们选择将这个亚基称为TCR的η链。在克隆和非克隆的T细胞群体中，90%的ζ以同二聚体形式存在，其余的则与η链相连。ζ-ζ与ζ-η比例的严格调控表明这些TCR结构成分具有重要的功能作用。
