biostudies-literatureUnknown53(3)Bennett WFDThe translocation of lipids across membranes (flip-flop) is an important biological process. Slow exchange on a physiological timescale allows the creation of asymmetric distributions of lipids across cellular membranes. The location of lipids and their rate of exchange have important biological consequences, especially for lipids involved in cellular signaling. We investigated the translocation of cholesterol, ceramide, and diacylglycerol in two model bilayers using molecular dynamics simulations. We estimate half times for flip-flop for cholesterol, diacylglycerol, and ceramide of 20 μs, 30 μs, and 10 ms in a POPC bilayer, compared with approximately 30 min, 30 ms, and 30 s in a model raft bilayer (1:1:1 PSM, POPC, and cholesterol). Cholesterol has a large (54 kJ/mol) free energy of exchJournal of lipid research421-429https://www.ebi.ac.uk/biostudies/studies/S-EPMC3276465biostudies-literatureMolecular simulation of rapid translocation of cholesterol, diacylglycerol, and ceramide in model raft and nonraft membranes.PMC3276465Bennett WFDTieleman DPfalseMolecular simulation of rapid translocation of cholesterol, diacylglycerol, and ceramide in model raft and nonraft membranes.The translocation of lipids across membranes (flip-flop) is an important biological process. Slow exchange on a physiological timescale allows the creation of asymmetric distributions of lipids across cellular membranes. The location of lipids and their rate of exchange have important biological consequences, especially for lipids involved in cellular signaling. We investigated the translocation of cholesterol, ceramide, and diacylglycerol in two model bilayers using molecular dynamics simulations. We estimate half times for flip-flop for cholesterol, diacylglycerol, and ceramide of 20 μs, 30 μs, and 10 ms in a POPC bilayer, compared with approximately 30 min, 30 ms, and 30 s in a model raft bilayer (1:1:1 PSM, POPC, and cholesterol). Cholesterol has a large (54 kJ/mol) free energy of exch2012-01-01T00:00:00Z2012 Mar2025-04-26T07:39:59.618Z2019-03-27T00:48:58ZS-EPMC32764652224684710.1194/jlr.M02249110.1194/jlr.m022491