Attractive membrane domains control lateral diffusion.
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.
Forstner
Martin B
MB
Center for Nonlinear Dynamics, University of Texas, R. L. Moore Building, Austin, Texas 78712, USA. mbf@berkeley.edu
Martin
Douglas S
DS
Rückerl
Florian
F
Käs
Josef A
JA
Selle
Carsten
C
D001704:Biopolymers / Q000737:chemistry*; D003198:Computer Simulation; D004058:Diffusion; D008051:Lipid Bilayers / Q000737:chemistry*; D008560:Membrane Fluidity; D021962:Membrane Microdomains / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular
D001704:Biopolymers; D008051:Lipid Bilayers