Glucosylceramide increases the mechanical resistance of membrane domains.

Cells tightly regulate membrane composition to maintain homeostasis and adapt to perturbations. Disruptions in lipid metabolism, such as those occurring in Gaucher disease (GD), can disturb this balance. In GD, excess glucosylceramide (GlcCer) accumulates in lysosomes, altering overall lipid metabolism and potentially impacting membrane composition. This study investigates how GlcCer influences lipid distribution and the local mechanical properties of model lipid bilayers composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), egg sphingomyelin (SME), cholesterol (Chol) and GlcCer in varying ratios, using atomic force microscopy and force spectroscopy. In simple bilayers (DOPC and DOPC:Chol), GlcCer forms rigid, unstable domains with high lateral packing. In contrast, in complex DOPC:Chol:SME membranes, higher GlcCer concentrations are accommodated but significantly alter domain organization and nanomechanical properties. Excess GlcCer preferentially partitions into segregated domains, sequestering cholesterol and SME, thereby reshaping lipid distribution with potential implications for membrane curvature, protein diffusion and localization.