AbstractSYNOPSIS. Cholesterol is an essential component in the plasma membranes of animals with multiple effects on the physical properties of membranes including membrane order (fluidity), phase behavior, thickness, and permeability. Cholesterol also affects functional attributes of cell membranes such as the activities of various integral proteins. Because cholesterol provides rigidity to fluid phase membranes, it is a likely candidate to counter some of the temperature-induced perturbations in membrane order that would otherwise be experienced by animals that live at varied body temperatures. If cholesterol contributes to homeoviscous adaptation (HVA), more cholesterol is likely to be present in plasma membranes from warm-bodied animals than from cold-bodied animals. This prediction is generally supported by studies examining cholesterol contents in membranes from endothermic and ectothermic animals. Comparisons of cholesterol levels in temperature acclimated (oracclimatized) ectotherms reveal an increase in cholesterol with temperature, no change in cholesterol content, or an increase in cholesterol with a decrease in temperature. These different patterns largely represent tissue and regional differences in the membranes (membrane domains). The membranespecific nature of the cholesterol response to temperature is likely to arise from the multiplicity of the effects that cholesterol exerts on membranes, as well as the heterogenous nature of plasma membranes. These factors also allow cholesterol to perform more than a single role in temperature adaptation of plasma membranes in animals. This content is only available as a PDF. Author notes1From the Symposium The Biology of Lipids: Integration of Structure and Function presented at the Annual Meeting of the Society for Integrative and Comparative Biology, 26–30 December 1996, Albuquerque, New Mexico. © 1998 by the Society for Integrative and Comparative Biology © 1998 by the Society for Integrative and Comparative Biology Definition
Related term(s): Last updated on July 28th, 2021 Cholesterol is an essential component of all animal cell membranes and plays an important role in maintaining the membrane structure and physical–chemical properties necessary for correct cell functioning. The presence of cholesterol is believed to be responsible for domain formation (lipid rafts) due to different interactions of cholesterol with saturated and unsaturated
lipids. In order to get detailed atomistic insight into the behaviour of cholesterol in bilayers composed of lipids with varying degrees of unsaturation, we have carried out a series of molecular dynamics simulations of saturated and polyunsaturated lipid bilayers with different contents of cholesterol, as well as well-tempered metadynamics simulations with a single cholesterol molecule in these bilayers. From these simulations we have determined distributions of cholesterol across the bilayer,
its orientational properties, free energy profiles, and specific interactions of molecular groups able to form hydrogen bonds. Both molecular dynamics and metadynamics simulations showed that the most unsaturated bilayer with 22:6 fatty acid chains shows behaviour which is most different from other lipids. In this bilayer, cholesterol is relatively often found in a “flipped” configuration with the hydroxyl group oriented towards the membrane middle plane. This bilayer has also the highest (least
negative) binding free energy among liquid phase bilayers, and the lowest reorientation barrier. Furthermore, cholesterol molecules in this bilayer are often found to form head-to-tail contacts which may lead to specific clustering behaviour. Overall, our simulations support ideas that there can be a subtle interconnection between the contents of highly unsaturated fatty acids and cholesterol, deficiency or excess of each of them is related to many human afflictions and diseases. Supplementary files
Article informationDOI https://doi.org/10.1039/C8SM01937AArticle type PaperSubmitted 21 Sep 2018Accepted 21 Nov 2018First published 23 Nov 2018This article is Open Access Download CitationSoft Matter, 2019,15, 78-93 Permissions
Cholesterol in phospholipid bilayers: positions and orientations inside membranes with different unsaturation degreesI. Ermilova and A. P. Lyubartsev, Soft Matter, 2019, 15, 78 DOI: 10.1039/C8SM01937A This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes. To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activitySpotlightAdvertisements |