Davis S J, Ikemizu S, Wild M K, van der Merwe P A
Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford, UK.
Immunol Rev. 1998 Jun;163:217-36. doi: 10.1111/j.1600-065x.1998.tb01199.x.
Rapid progress has recently been made in characterising the structures of leukocyte cell-surface molecules. Detailed analyses of the structure and interactions of CD2 were the first involving a molecule that has not been directly linked to antigen recognition in the manner of antigen receptors or co-receptors. It seems highly likely that the properties of ligand binding by CD2 are relevant to the general mechanisms of cell-cell recognition. As an example of biological recognition, the defining characteristic of cell-cell contact is that it involves the simultaneous interaction of hundreds, if not thousands, of molecules. Affinity and kinetic analyses of ligand binding by CD2 indicated that the protein interactions mediating cell-cell contact, whilst highly specific, are much weaker than initially anticipated, probably due to the requirement that such contacts be easily reversible. Simultaneously, in addressing the mechanism of this mode of recognition, structural and mutational studies focussed on the role of charged residues clustered in the ligand-binding face of CD2, yielding the concept that electrostatic complementarity, rather than surface-shape complementarity, is the dominant feature of specific, low-affinity protein recognition at the cell surface by CD2. The crystallographic analysis of the CD2-binding domain of CD58 strongly supports this concept.
最近在白细胞细胞表面分子结构的表征方面取得了快速进展。对CD2结构及其相互作用的详细分析是首次涉及一个尚未以抗原受体或共受体的方式直接与抗原识别相关联的分子。CD2的配体结合特性极有可能与细胞间识别的一般机制相关。作为生物识别的一个例子，细胞间接触的决定性特征是它涉及数百个（如果不是数千个）分子的同时相互作用。对CD2配体结合的亲和力和动力学分析表明，介导细胞间接触的蛋白质相互作用虽然高度特异性，但比最初预期的要弱得多，这可能是由于这种接触需要易于逆转。同时，在研究这种识别模式的机制时，结构和突变研究集中在CD2配体结合面上聚集的带电残基的作用上，得出这样一个概念，即静电互补性而非表面形状互补性是CD2在细胞表面进行特异性、低亲和力蛋白质识别的主要特征。CD58的CD2结合域的晶体学分析有力地支持了这一概念。
