Clarris H J, Cappai R, Heffernan D, Beyreuther K, Masters C L, Small D H
Department of Pathology, University of Melbourne, Parkville, Victoria, Australia.
J Neurochem. 1997 Mar;68(3):1164-72. doi: 10.1046/j.1471-4159.1997.68031164.x.
Recent studies have shown that the binding of the amyloid protein precursor (APP) of Alzheimer's disease to heparan sulfate proteoglycans (HSPGs) can modulate a neurite outgrowth-promoting function associated with APP. We used three different approaches to identify heparin-binding domains in APP. First, as heparin-binding domains are likely to be within highly folded regions of proteins, we analyzed the secondary structure of APP using several predictive algorithms. This analysis showed that two regions of APP695 contain a high degree of secondary structure, and clusters of basic residues, considered mandatory for heparin binding, were found, principally within these regions. To determine which domains of APP bind heparin, deletion mutants of APP695 were prepared and analyzed for binding to a heparin affinity column. The results suggested that there must be at least two distinct heparin-binding regions in APP. To identify novel heparin-binding regions, peptides homologous to candidate heparin-binding domains were analyzed for their ability to bind heparin. These experiments suggested that APP contains at least four heparin-binding domains. The presence of more than one heparin-binding domain on APP suggests the possibility that APP may interact with more than one type of glycosaminoglycan.
最近的研究表明，阿尔茨海默病的淀粉样蛋白前体（APP）与硫酸乙酰肝素蛋白聚糖（HSPG）的结合可以调节与APP相关的促进神经突生长的功能。我们使用了三种不同的方法来鉴定APP中的肝素结合结构域。首先，由于肝素结合结构域可能位于蛋白质的高度折叠区域内，我们使用几种预测算法分析了APP的二级结构。该分析表明，APP695的两个区域具有高度的二级结构，并且发现了被认为是肝素结合所必需的碱性残基簇，主要在这些区域内。为了确定APP的哪些结构域结合肝素，制备了APP695的缺失突变体并分析其与肝素亲和柱的结合。结果表明，APP中必须至少有两个不同的肝素结合区域。为了鉴定新的肝素结合区域，分析了与候选肝素结合结构域同源的肽结合肝素的能力。这些实验表明，APP至少包含四个肝素结合结构域。APP上存在多个肝素结合结构域表明APP可能与不止一种类型的糖胺聚糖相互作用。
