Attractive membrane domains control lateral diffusion

Author :Martin B. Forstner, Douglas S. Martin, Florian Rückerl, Josef A. Kas, and Carsten Selle
Publication :Physical Review E
Publisher :The American Physical Society
Volume :77
Pages :051906
Year :2008

Lipid membranes play a fundamental role in vital cellular functions such as signal transduction. Many of
these processes rely on lateral diffusion within the membrane, generally a complex fluid containing ordered
microdomains. However, little attention has been paid to the alterations in transport dynamics of a diffusing
species caused by long-range interactions with membrane domains. In this paper, we address the effect of such
interactions on diffusive transport by studying lateral diffusion in a phase-separated Langmuir phospholipid
monolayer via single-particle tracking. We find that attractive dipole-dipole interactions between condensed
phase domains and diffusing probe beads lead to transient confinement at the phase boundaries, causing a
transition from two- to one-dimensional diffusion. Using Brownian dynamics simulations, the long-term diffusion
constant for such a system is found to have a sensitive, Boltzmann-like, dependence on the interaction
strength. In addition, this interaction strength is shown to be a strong function of the ratio of domain to particle
size. As similar interactions are expected in biological membranes, the modulation of diffusive transport
dynamics by varying interaction strength and/or domain size may offer cells selective spatial and temporal
control over signaling processes.