Hydrated networks of glycans in the form of cell walls, periplasms, or gel-like matrices are ubiquitously present adjacent to cellular plasma membranes. Yet despite their abundance, many of the functions of glycans in the extracellular milieu are unknown. Eukaryotic cells compartmentalize their membranes to carry out biological function. These domains are important for signal transduction, virus entry and budding, and for the development of degenerative diseases such as Alzheimer’s. The factors that govern the formation of these membrane domains are also incompletely understood. In this talk I will describe an experimental platform that consists of spatially patterned glycan ligands on hydrophilic surfaces. Lipid membranes that are deposited onto these surfaces appear to interact directly with these glycans. Because of this interaction, the spatial configuration of the glycans control the phase behavior of the membranes: inhomogeneous glycan networks stabilize large lipid domains at the characteristic length scale of the network, while homogeneous glycan networks suppress macroscopic lipid phase separation. Glycan-patterned phase separation is thermally reversible—indicating that the effect is thermodynamic rather than kinetic—and preferential interactions of glycan with ordered lipid phases seem to control patterning. The discovery that glycan networks can control the length scale of domains in lipid membranes necessarily has implications for biological transport processes and potentially rationalizes some puzzling observations that differentiate the behavior of native cell membranes from model membranes. The exact nature of the interactions remains to be elucidated, and may be related to other observations of lipid domain patterning due to interactions of membranes with cytoskeleton proteins.<br/>

Glycan density controls the phase behavior of lipid membranes

251st National Meeting (2016)

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