Jefferis R, Lund J, Mizutani H, Nakagawa H, Kawazoe Y, Arata Y, Takahashi N
Department of Immunology, University of Birmingham Medical School, Edgbaston, U.K.
Biochem J. 1990 Jun 15;268(3):529-37. doi: 10.1042/bj2680529.
Quantitative oligosaccharide profiles were determined for each of 18 human IgG paraproteins representing the four subclasses. Each paraprotein exhibits a unique profile that may be substantially different from that observed for polyclonal IgG. The IgG2 and some IgG3 proteins analysed exhibit a predominance of oligosaccharide moieties having galactose on the Man(alpha 1----3) arm rather than the Man(alpha 1----6) arm; it was previously held that galactosylation of the Man(alpha 1----6) arm is preferred, as observed for IgG1, IgG4 and polyclonal IgG. An IgG4 protein is reported that has galactosylated Man(alpha 1----3) and Man(alpha 1----6) arms on both Fc-localized carbohydrate moieties; previous findings suggested that such fully glycosylated structures could not be accommodated within the internal space of the C gamma 2 domains. Unusual monoantennary oligosaccharides present in IgG2 and IgG3 proteins were isolated and their structures determined.
对代表四种亚类的18种人IgG副蛋白分别测定了寡糖定量图谱。每种副蛋白都呈现出独特的图谱，可能与多克隆IgG所观察到的图谱有很大不同。所分析的IgG2和一些IgG3蛋白显示，在Man(α1----3)臂而非Man(α1----6)臂上具有半乳糖的寡糖部分占优势；以前认为，如在IgG1、IgG4和多克隆IgG中所观察到的那样，Man(α1----6)臂的半乳糖基化是优选的。据报道，一种IgG4蛋白在两个Fc定位的碳水化合物部分的Man(α1----3)和Man(α1----6)臂上都有半乳糖基化；以前的研究结果表明，这种完全糖基化的结构无法容纳在Cγ2结构域的内部空间中。分离出了IgG2和IgG3蛋白中存在的不寻常的单天线寡糖并确定了它们的结构。
