Three-dimensional structure of glycolipids in biological membranes.

Characterizing the structure-function relationships of glycolipids in lipid membranes is a challenging endeavor. Glycolipid "structure" is rarely, if ever, a unique low-energy conformer, but an ensemble of dynamic states, which vary in their presentation of binding epitopes. The modulation of binding epitopes not only is an internal process but also is influenced by external factors such as glycolipid clustering and fluctuations in and composition of the fluid membrane environment. As with other glyco-conjugates, three-dimensional structural elucidation has relied heavily on nuclear magnetic resonance spectroscopy and computational modeling. Discrete conformational states can be discerned from motion-averaged experimental data by employing independent molecular dynamics simulations. Using model membranes such as micelles, bicelles, and bilayers, we can approximate the effect of their biological environment and quantify cell-surface presentation.