School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Nat Mater. 2013 Feb;12(2):128-33. doi: 10.1038/nmat3492. Epub 2012 Nov 25.
Hydrated networks of glycans (polysaccharides)--in the form of cell walls, periplasms or gel-like matrices--are ubiquitously present adjacent to cellular plasma membranes. Yet, despite their abundance, the function of glycans in the extracellular milieu is largely unknown. Here we show that the spatial configuration of glycans controls the phase behaviour of multiphase model lipid membranes: inhomogeneous glycan networks stabilize large lipid domains at the characteristic length scale of the network, whereas homogeneous networks suppress macroscopic lipid phase separation. We also find that glycan-patterned phase separation is thermally reversible--thus indicating that the effect is thermodynamic rather than kinetic--and that phase patterning probably results from a preferential interaction of glycans with ordered lipid phases. These findings have implications for membrane-mediated transport processes, potentially rationalize long-standing observations that differentiate the behaviour of native and model membranes and may indicate an intimate coupling between cellular lipidomes and glycomes.
糖链（多糖）的水合网络——以细胞壁、周质或凝胶状基质的形式——普遍存在于细胞膜的邻近部位。然而，尽管它们的数量很多，但糖链在细胞外环境中的功能在很大程度上仍是未知的。在这里，我们表明，糖链的空间构象控制着多相模型脂质膜的相行为：不均匀的糖链网络在网络的特征长度尺度上稳定大的脂质域，而均匀的网络则抑制宏观脂质相分离。我们还发现，糖链图案化的相分离是热可逆的——因此表明这种效应是热力学的而不是动力学的——而且相图案化可能是由于糖链与有序脂质相的优先相互作用所致。这些发现对膜介导的运输过程具有影响，可能解释了区分天然和模型膜行为的长期观察结果，并可能表明细胞脂类组和糖组之间存在密切的耦合。
