ИСТИНА

Membrane rafts are small (10-200 nm), heterogeneous, highly dynamic, cholesterol and sphingolipid-enriched domains that compartmentalize cellular processes. Rafts are implicated in membrane trafficking, signal transduction, including immune response, and entry and budding of pathogens. At the same time small rafts could be stabilized forming larger platforms through protein-protein and protein-lipid interactions. In this work, we focused on large-scale molecular dynamics (MD) simulations of raft formation in model membranes and quantitative description of interactions between different types of lipids. We simulated bilayer systems containing binary and ternary mixtures of saturated and unsaturated lipids and cholesterol (Chol) and performed metadynamics simulations to determine free energy profiles of interaction of lipid species forming rafts. We observed spontaneous raft formation in ternary system with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), cholesterol and D-erythro-n-palmitoyl-sphingomyelin (SM) in ratio 2:1:1. The coexistence of both the Lo/Ld phases in ternary system was reproduced. Also we found specific interaction mode between sphingomyelin and cholesterol providing insight into raft microstructure.