Background: Gangliosides are an essential component of eukaryotic plasma membranes implicated in multiple physiological processes. Little is known about molecular mechanisms underlying the distribution and functions of membrane gangliosides. The overwhelmingly complex organization of glycocalyx impedes the structural analysis on cell surface and the interplay between the lipid components. Advanced X-ray analytical tools applicable to studying biological interfaces call for the simplistic models that mimic ganglioside-enriched cellular membranes.

Objective: To summarize the mechanistic evidences of ganglioside interactions with lipid environment and biologically active ligands using high-resolution synchrotron X-ray scattering.

Methods: A comprehensive review of studies published over the last decade was done to discuss recent accomplishments and future trends.

Results: Langmuir monolayers represent an adequate model system to assess the effect of gangliosides on membrane structure. Grazing incidence X-ray diffraction reveals a condensation effect by gangliosides on zwitterionic phospholipids with the cooperative packing of sialo- and phosphate groups. In turn, the arrangement of negatively charged lipids in ganglioside mixture remains unchanged due to the stretched conformation of carbohydrate moieties. Upon interaction with biological ligands, such as cholera toxin and galectins, the ganglioside redistribution within the ordered regions of monolayer follows distinct mechanistic patterns. The cholera toxin pentamer attached to the oligosaccharide core induces local transition from oblique to the hexagonal lattice resulting in phase coexistence. The incorporation of the A subunit responsible for endocytosis is further promoted by the acidic environment characteristic for endosomal space. X-ray reflectivity shows in-plane orientation of galectin dimers with the spatial mismatch between the lectin binding sites and ganglioside carbohydrates to perturb ceramide alkyl chains. Recent data also demonstrate sialic acid groups to be potential targets for novel peptide mimicking anticancer therapeutics.

Conclusion: Coupled with surface X-ray scattering, the membrane mimetic approach allows for better understanding the biological role of gangliosides and their potential applications.

背景：神经节苷脂是真核细胞质膜的重要组成部分，与多种生理过程有关。关于膜神经节苷脂的分布和功能的分子机制知之甚少。糖萼的极其复杂的组织阻碍了细胞表面的结构分析以及脂质成分之间的相互作用。适用于研究生物界面的高级X射线分析工具需要模拟富含神经节苷脂的细胞膜的简单模型。

目的：利用高分辨率同步加速器X射线散射总结神经节苷脂与脂质环境和生物活性配体相互作用的机理证据。

方法：对过去十年发表的研究进行了全面回顾，以讨论最新成就和未来趋势。

结果：Langmuir单层膜代表了评估神经节苷脂对膜结构影响的适当模型系统。掠入射X射线衍射揭示神经节苷脂对两性离子磷脂的缩合作用，并带有唾液酸基团和磷酸基团的协同堆积。继而，由于碳水化合物部分的伸展构象，神经节苷脂混合物中带负电荷的脂质的排列保持不变。与诸如霍乱毒素和半乳糖凝集素等生物配体相互作用后，神经节苷脂在单层有序区域内的重新分布遵循不同的机理模式。附着在寡糖核心上的霍乱毒素五聚体诱导从斜向六边形晶格的局部转变，导致相共存。内吞空间的酸性环境特征进一步促进了负责内吞作用的A亚基的掺入。X射线反射率显示了半乳凝素二聚体的面内取向，其中凝集素结合位点和神经节苷脂碳水化合物之间的空间失配干扰了神经酰胺烷基链。最近的数据也证明唾液酸基团是模仿抗癌治疗剂的新型肽的潜在靶标。

结论：结合表面X射线散射，膜模拟方法可以更好地了解神经节苷脂的生物学作用及其潜在应用。