Fields B A, Ober B, Malchiodi E L, Lebedeva M I, Braden B C, Ysern X, Kim J K, Shao X, Ward E S, Mariuzza R A
Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, MD 20850, USA.
Science. 1995 Dec 15;270(5243):1821-4. doi: 10.1126/science.270.5243.1821.
The crystal structure of the V alpha domain of a T cell antigen receptor (TCR) was determined at a resolution of 2.2 angstroms. This structure represents an immunoglobulin topology set different from those previously described. A switch in a polypeptide strand from one beta sheet to the other enables a pair of V alpha homodimers to pack together to form a tetramer, such that the homodimers are parallel to each other and all hypervariable loops face in one direction. On the basis of the observed mode of V alpha association, a model of an (alpha beta)2 TCR tetramer can be positioned relative to the major histocompatibility complex class II (alpha beta)2 tetramer with the third hypervariable loop of V alpha over the amino-terminal portion of the antigenic peptide and the corresponding loop of V beta over its carboxyl-terminal residues. TCR dimerization that is mediated by the alpha chain may contribute to the coupling of antigen recognition to signal transduction during T cell activation.
T细胞抗原受体（TCR）的Vα结构域的晶体结构在2.2埃的分辨率下得以确定。该结构代表了一种不同于先前描述的免疫球蛋白拓扑结构。一条多肽链从一个β折叠转换到另一个β折叠，使得一对Vα同型二聚体能够堆积在一起形成四聚体，从而使同型二聚体彼此平行，且所有高变环都朝一个方向。基于观察到的Vα缔合模式，（αβ）2 TCR四聚体的模型可以相对于主要组织相容性复合体II类（αβ）2四聚体进行定位，其中Vα的第三个高变环位于抗原肽的氨基末端部分上方，Vβ的相应环位于其羧基末端残基上方。由α链介导的TCR二聚化可能有助于在T细胞活化过程中将抗原识别与信号转导偶联起来。
