title: Cholesterol translocation in a phospholipid membrane.
abstract: Cholesterol (CHOL) molecules play a key role in modulating the rigidity of cell membranes and controlling intracellular transport and signal transduction. Using an all-atom molecular dynamics approach, we study the process of CHOL interleaflet transport (flip-flop) in a dipalmitoylphosphatidycholine (DPPC)-CHOL bilayer over a time period of 15 μs. We investigate the effect of the flip-flop process on mechanical stress across the bilayer and the role of CHOL in inducing molecular order in bilayer leaflets. The simulations are carried out at physiologically relevant CHOL concentration (30%), temperature (323 K), and pressure (1 bar). CHOL flip-flop events are observed with a rate constant of 3 × 10⁴s⁻¹. Once a flip-flop event is triggered, a CHOL molecule takes an average of 73 nanoseconds to migrate from one bilayer leaflet to the other.
authors.affiliation: Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Choubey
authors.forename: Rajiv K
authors.initials: RK
authors.lastname: Kalia
authors.forename: Noah
authors.initials: N
authors.lastname: Malmstadt
authors.forename: Aiichiro
authors.initials: A
authors.lastname: Nakano
authors.forename: Priya
authors.initials: P
authors.lastname: Vashishta
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism*; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D011312:Pressure
chemical_list: D015060:1,2-Dipalmitoylphosphatidylcholine; D002784:Cholesterol