Loveless R W, Holmskov U, Feizi T
Glycosciences Laboratory, Northwick Park Hospital, Harrow, UK.
Immunology. 1995 Aug;85(4):651-9.
Collectin-43 (CL-43) is a C-type serum lectin and a member of the collectin family of soluble proteins that are effector molecules in innate immunity. We have investigated the binding specificity of CL-43 using as model systems a panel of structurally defined oligosaccharides in the form of neoglycolipids, and several glycoproteins derived from the complement glycoprotein C3 during activation of the complement cascade. A specificity is revealed towards fucose as part of the Lea oligosaccharide sequence, and towards mannose as found on high mannose-type chains. These are features shared with other serum collectins, conglutinin and mannan-binding proteins; a major difference is the lack of detectable binding by CL-43 to N-glycosidic oligosaccharides terminating in N-acetylglucosamine. CL-43 has a unique pattern of reactivity towards high mannose-type oligosaccharides on the two glycosylation sites of C3 and derived glycoproteins: it binds to C3c (not bound by conglutinin and mannan-binding protein) but not to hydrolysed C3 [C3(H2O)], C3b or iC3b immobilized on microwells (all bound by conglutinin but not by mannan-binding protein). When these glycoproteins are sodium dodecyl sulphate (SDS)-treated and immobilized on nitrocellulose, CL-43 (but not conglutinin nor mannan-binding protein) binds strongly to C3(H2O), iC3b and C3c. The salient conclusions are, first, that there are remarkable positive or negative effects of carrier protein on oligosaccharide presentation and these differ for the individual collectins. Second, the different though partially overlapping binding patterns among the collectins may be important for their function as circulating effector molecules with broad surveillance capabilities.
Collectin-43（CL-43）是一种C型血清凝集素，属于可溶性蛋白的collectin家族成员，是天然免疫中的效应分子。我们以新糖脂形式的一组结构明确的寡糖以及补体级联激活过程中源自补体糖蛋白C3的几种糖蛋白为模型系统，研究了CL-43的结合特异性。结果显示，CL-43对作为Lea寡糖序列一部分的岩藻糖以及高甘露糖型链上的甘露糖具有特异性。这些是其他血清collectin、胶固素和甘露糖结合蛋白共有的特征；一个主要区别是CL-43未检测到与以N-乙酰葡糖胺结尾的N-糖苷寡糖的结合。CL-43对C3和衍生糖蛋白的两个糖基化位点上的高甘露糖型寡糖具有独特的反应模式：它与C3c结合（胶固素和甘露糖结合蛋白不结合），但不与固定在微孔板上的水解C3 [C3(H2O)]、C3b或iC3b结合（胶固素结合但甘露糖结合蛋白不结合）。当这些糖蛋白用十二烷基硫酸钠（SDS）处理并固定在硝酸纤维素上时，CL-43（但胶固素和甘露糖结合蛋白不）与C3(H2O)、iC3b和C3c强烈结合。主要结论是，首先，载体蛋白对寡糖呈现具有显著的正向或负向影响，且这些影响因个体collectin而异。其次，collectin之间不同但部分重叠的结合模式可能对它们作为具有广泛监测能力的循环效应分子的功能很重要。
