writer：Yong-Hao Ma, Bolin Li, Chu Wang, Jingjing Yang, Xiaofeng Han, and Xiaolin Lu*
keywords：Nonlinear optical processes, Mass diffusivity, Sum frequency generation spectroscopy, Lipids, Membrane potential, Cell membranes
source：期刊
Issue time：2024年

Within cell plasma membranes, unsaturated lipids are asymmetrically distributed over the inner and outer leaflets, offering an attractive local structural feature. However, the mechanism to keep lipid transmembrane asymmetry and the closely related transmembrane movement (flip-flop) for unsaturated lipids remain poorly understood. Here, we applied sum frequency generation vibrational spectroscopy to investigate this lipid transmembrane asymmetry upon mimicking the cell membrane homeostatic processes. On the one hand, unsaturated lipids were found to hinder the flip-flop process and preserve lipid transmembrane asymmetry in model cell membranes, owing to the steric hindrance caused by their bent tails. On the other hand, local unsaturated lipids in the mixed unsaturated/saturated lipid bilayer were conducive to the formation of the local asymmetry. Therefore, lipid unsaturation can be recognized as an intrinsic key factor to form and maintain lipid transmembrane asymmetry in cell membranes.

https://pubs.aip.org/aip/jcp/article/160/21/215102/3296412/Unsaturation-effects-on-lipid-transmembrane