Adhesive switching of membranes: Experiment and theory

Robijn Bruinsma, Almuth Behrisch, and Erich Sackmann
Phys. Rev. E 61, 4253 – Published 1 April 2000
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Abstract

We report on a study of a model bioadhesion system: giant vesicles in contact with a supported lipid bilayer. Embedded in both membranes are very low concentrations of homophilic recognition molecules (contact site A receptors) competing with higher concentrations of repeller molecules: polyethylene glycol (PEG) lipids. These repellers mimic the inhibiting effect of the cell glycocalyx on adhesion. The effective adhesive interaction between the two membranes is probed by interferometric analysis of thermal fluctuations. We find two competing states of adhesion: initial weak adhesion is followed by slower aggregation of the adhesion molecules into small, tightly bound clusters that coexist with the regions of weak adhesion. We interpret our results in terms of a double-well intermembrane potential, and we present a theoretical analysis of the intermembrane interaction in the presence of mobile repeller molecules at a fixed chemical potential that shows that the interaction potential indeed should have just such a double-well shape. At a fixed repeller concentration we recover a conventional purely repulsive potential. We discuss the implications of our findings in terms of a general amplification mechanism of the action of sparse adhesion molecules by a nonspecific double-well potential. We also discuss the important role of the Helfrich undulation force for the proposed scenario.

  • Received 6 August 1999

DOI:https://doi.org/10.1103/PhysRevE.61.4253

©2000 American Physical Society

Authors & Affiliations

Robijn Bruinsma1, Almuth Behrisch2, and Erich Sackmann2,*

  • 1Department of Physics, University of California, Los Angeles, California 90024
  • 2Physik Department, E22 (Biophysical Laboratory), Technische Universität München, James Franck Straße, D-85747 Garching, Germany

  • *Author to whom correspondence should be addressed.

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Vol. 61, Iss. 4 — April 2000

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