Volume 144, 2010

Concerted diffusion of lipids in raft-like membranes

Abstract

Currently, there is no comprehensive model for the dynamics of cellular membranes. The understanding of even the basic dynamic processes, such as lateral diffusion of lipids, is still quite limited. Recent studies of one-component membrane systems have shown that instead of single-particle motions, the lateral diffusion is driven by a more complex, concerted mechanism for lipid diffusion (E. Falck et al., J. Am. Chem. Soc., 2008, 130, 44–45), where a lipid and its neighbors move in unison in terms of loosely defined clusters. In this work, we extend the previous study by considering the concerted lipid diffusion phenomena in many-component raft-like membranes. This nature of diffusion phenomena emerge in all the cases we have considered, including both atom-scale simulations of lateral diffusion within rafts and coarse-grained MARTINI simulations of diffusion in membranes characterized by coexistence of raft and non-raft domains. The data allows us to identify characteristic time scales for the concerted lipid motions, which turn out to range from hundreds of nanoseconds to several microseconds. Further, we characterize typical length scales associated with the correlated lipid diffusion patterns and find them to be about 10 nm, or even larger if weak correlations are taken into account. Finally, the concerted nature of lipid motions is also found in dissipative particle dynamics simulations of lipid membranes, clarifying the role of hydrodynamics (local momentum conservation) in membrane diffusion phenomena.

Article information

Article type
Paper
Submitted
23 Jan 2009
Accepted
25 Mar 2009
First published
15 Aug 2009

Faraday Discuss., 2010,144, 411-430

Concerted diffusion of lipids in raft-like membranes

T. Apajalahti, P. Niemelä, P. N. Govindan, M. S. Miettinen, E. Salonen, S. Marrink and I. Vattulainen, Faraday Discuss., 2010, 144, 411 DOI: 10.1039/B901487J

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