Biomembranes exhibit liquid and solid features concomitantly with their in-plane fluidity and elasticity tightly regulated by cells. Whether the two features are correlated and co-regulated is a question of fundamental importance and with broad implications. Here, through electron spin resonance and analyses on the experimental data in literature, we examine the composition dependence of the in-plane dynamics and elastic properties of lipid membranes. The results support the existence of the dynamics-elasticity correlations for lipid membranes, and the correlations can be explained with a mechanism involving lipid molecular packing densities. This study thereby unifies, at the molecular level, the aspects of the continuum mechanics long used to model the two membrane features. We raise the possibility that the known cellular regulations on membrane fluidity and elasticity are merely two manifestations of the membrane homeostasis that regulates the molecular packing densities; and fluctuations in membrane packing densities may be responsible for the known dynamic, elastic, and functional couplings of lipids and proteins. The understanding delineates a unified perspective on the cellular processes involving biomembranes.

Coupling of lipid membrane elasticity and dynamics

255th National Meeting (2018)

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