Sparrow Lindsay G, Gorman Jeffrey J, Strike Phillip M, Robinson Christine P, McKern Neil M, Epa V Chandana, Ward Colin W
Commonwealth Scientific and Industrial Research Organisation, Molecular and Health Technologies, Parkville, Victoria 3052, Australia.
Proteins. 2007 Feb 1;66(2):261-5. doi: 10.1002/prot.21261.
O-linked glycosylation is a post-translational and post-folding event involving exposed S/T residues at beta-turns or in regions with extended conformation. O-linked sites are difficult to predict from sequence analyses compared to N-linked sites. Here we compare the results of chemical analyses of isolated glycopeptides with the prediction using the neural network prediction method NetOGlyc3.1, a procedure that has been reported to correctly predict 76% of O-glycosylated residues in proteins. Using the heavily glycosylated human insulin receptor as the test protein six sites of mucin-type O-glycosylation were found at residues T744, T749, S757, S758, T759, and T763 compared to the three sites (T759 and T763- correctly, T756- incorrectly) predicted by the neural network method. These six sites occur in a 20 residue segment that begins nine residues downstream from the start of the insulin receptor beta-chain. This region which also includes N-linked glycosylation sites at N742 and N755, is predicted to lack secondary structure and is followed by residues 765-770, the known linear epitope for the monoclonal antibody 18-44.
O-连接糖基化是一种翻译后和折叠后事件，涉及β-转角处或具有伸展构象区域中暴露的丝氨酸/苏氨酸残基。与N-连接位点相比，O-连接位点很难通过序列分析来预测。在这里，我们将分离的糖肽的化学分析结果与使用神经网络预测方法NetOGlyc3.1的预测结果进行比较，据报道该方法能正确预测蛋白质中76%的O-糖基化残基。以高度糖基化的人胰岛素受体作为测试蛋白，发现了6个粘蛋白型O-糖基化位点，分别位于残基T744、T749、S757、S758、T759和T763，而神经网络方法预测的3个位点（T759和T763正确，T756错误）。这6个位点位于一个20个残基的片段中，该片段从胰岛素受体β链起始点下游9个残基处开始。该区域还包括N742和N755处的N-连接糖基化位点，预计缺乏二级结构，其后是残基765 - 770，这是单克隆抗体18 - 44已知的线性表位。
