Permeability of membranes in the liquid ordered and liquid disordered phases.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31819053.
- Also identified by DOI 10.1038/s41467-019-13432-7 and PMC identifier 6901538.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The functional significance of ordered nanodomains (or rafts) in cholesterol rich eukaryotic cell membranes has only begun to be explored. This study exploits the correspondence of cellular rafts and liquid ordered (L<sub>o</sub>) phases of three-component lipid bilayers to examine permeability. Molecular dynamics simulations of L<sub>o</sub> phase dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylcholine (DOPC), and cholesterol show that oxygen and water transit a leaflet through the DOPC and cholesterol rich boundaries of hexagonally packed DPPC microdomains, freely diffuse along the bilayer midplane, and escape the membrane along the boundary regions. Electron paramagnetic resonance experiments provide critical validation: the measured ratio of oxygen concentrations near the midplanes of liquid disordered (L<sub>d</sub>) and L<sub>o</sub> bilayers of DPPC/DOPC/cholesterol is 1.75 ± 0.35, in very good agreement with 1.3 ± 0.3 obtained from simulation. The results show how cellular rafts can be structurally rigid signaling platforms while remaining nearly as permeable to small molecules as the L<sub>d</sub> phase.
Medical subject headings
- Cell Membrane Permeability