Department of Immunochemistry and Glycobiology, Institute for the Application of Nuclear Energy, INEP, University of Belgrade, Banatska 31b, 11080, Belgrade, Serbia.
Department of Immunochemistry and Glycobiology, Institute for the Application of Nuclear Energy, INEP, University of Belgrade, Banatska 31b, 11080, Belgrade, Serbia.
Arch Biochem Biophys. 2018 Sep 1;653:113-120. doi: 10.1016/j.abb.2018.06.017. Epub 2018 Jun 30.
Mucin 16 (MUC16) is a transmembrane type mucin and its released extracellular portion is designated as CA125 antigen. It is considered to be part of a supramolecular glycoprotein complex having a complicated epitope map and extreme structural heterogeneity. Starting from the initial transmembrane localization of MUC16/CA125 antigen and its alternative routes of release by shedding or putative secretion, CA125 antigen from human amniotic fluid soluble and extracellular vesicles (EVs)-containing fractions were characterized aiming at the possible glycosylation-associated mode of distribution as a factor contributing to the reported conflicting structural data. Ultracentrifugation, sucrose density gradient centrifugation, ion-exchange chromatography and TEM were used for analysis. The results indicated that the smeared abundantly glycosylated high molecular mass CA125-immunoreactive species, which follow the wheat germ agglutinin-binding pattern, were shared across amniotic fluid soluble and particulate fractions. A lower molecular mass glycoprotein-like CA125-immunoreactive species which follows the peanut agglutinin-binding pattern and was specifically associated with the EVs-enriched fraction was observed. CA125 presentation in the particulate amniotic fluid fraction was found to be shaped by a complex interactome partially involving lactose-sensitive galectin-3 binding. The MUC16 - EVs alliance as well as heterogeneous mucin/macromolecular complexes, at membranes or extracellularly, may represent cryptic pools of distinct CA125 species.
黏蛋白 16（MUC16）是一种跨膜型黏蛋白，其释放的细胞外部分被指定为 CA125 抗原。它被认为是具有复杂表位图谱和极端结构异质性的超分子糖蛋白复合物的一部分。从 MUC16/CA125 抗原的初始跨膜定位及其通过脱落或假定分泌的替代释放途径开始，对人羊水可溶性和含有细胞外囊泡（EVs）的级分中的 CA125 抗原进行了表征，目的是研究可能与糖基化相关的分布模式作为导致报告的结构数据冲突的因素。使用超速离心、蔗糖密度梯度离心、离子交换色谱和 TEM 进行分析。结果表明，大量糖基化的高分子质量 CA125 免疫反应性物质呈现出与麦芽凝集素结合模式一致的弥散模式，在羊水可溶性和颗粒性级分中都有分布。观察到一种低分子质量糖蛋白样 CA125 免疫反应性物质，其与花生凝集素结合模式一致，并且与富含 EVs 的级分特异性相关。发现颗粒状羊水级分中的 CA125 呈现有部分涉及乳糖敏感半乳糖凝集素-3 结合的复杂相互作用组。MUC16-EVs 联盟以及在膜上或细胞外的异质黏蛋白/大分子复合物可能代表不同 CA125 物质的隐匿性池。
