Parry Simon, Hanisch Franz Georg, Leir Shih-Hsing, Sutton-Smith Mark, Morris Howard R, Dell Anne, Harris Ann
Division of Molecular Biosciences, Imperial College London, UK.
Glycobiology. 2006 Jul;16(7):623-34. doi: 10.1093/glycob/cwj110. Epub 2006 Apr 3.
The MUC1 mucin is an important tumor-associated antigen that shows extensive glycosylation in vivo. The O-glycosylation of this molecule, which has been well characterized in many cell types and tissues, is important in conferring the unusual biochemical and biophysical properties on a mucin. N-Glycosylation is crucial to the folding, sorting, membrane trafficking, and secretion of many proteins. Here, we evaluated the N-glycosylation of MUC1 derived from two sources: endogenous MUC1 isolated from human milk and a recombinant epitope-tagged MUC1F overexpressed in Caco2 colon carcinoma cells. N-Glycans on purified MUC1F/MUC1 were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), gas chromatography-mass spectrometry (GC-MS), and CAD-ESI-MS/MS. The spectra indicate that MUC1F N-glycans have compositions consistent with high-mannose structures (Hex(5-9)HexNAc(2)) and complex/hybrid-type glycans (NeuAc(0-3)Fuc(0-3)Hex(3-8)HexNAc(3-7)). Many of the N-glycan structures are identical on MUC1F and native MUC1; however, a marked difference is seen between the N-glycans on membrane-bound and secreted forms of the native molecule.
黏蛋白1（MUC1）是一种重要的肿瘤相关抗原，在体内表现出广泛的糖基化。该分子的O-糖基化在许多细胞类型和组织中已得到充分表征，对于赋予黏蛋白异常的生化和生物物理特性很重要。N-糖基化对于许多蛋白质的折叠、分选、膜运输和分泌至关重要。在这里，我们评估了源自两种来源的MUC1的N-糖基化：从人乳中分离的内源性MUC1和在Caco2结肠癌细胞中过表达的重组表位标签化MUC1F。通过基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF-MS）、气相色谱-质谱（GC-MS）和CAD-ESI-MS/MS分析纯化的MUC1F/MUC1上的N-聚糖。光谱表明，MUC1F N-聚糖的组成与高甘露糖结构（Hex(5-9)HexNAc(2)）以及复杂/杂合型聚糖（NeuAc(0-3)Fuc(0-3)Hex(3-8)HexNAc(3-7)）一致。MUC1F和天然MUC1上的许多N-聚糖结构相同；然而，在天然分子的膜结合形式和分泌形式的N-聚糖之间存在明显差异。
