TY - JOUR
T1 - Adhesive switching of membranes
T2 - Experiment and theory
AU - Bruinsma, Robijn
AU - Behrisch, Almuth
AU - Sackmann, Erich
PY - 2000
Y1 - 2000
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0034173153&partnerID=8YFLogxK
U2 - 10.1103/PhysRevE.61.4253
DO - 10.1103/PhysRevE.61.4253
M3 - Article
C2 - 11088221
AN - SCOPUS:0034173153
SN - 1063-651X
VL - 61
SP - 4253
EP - 4267
JO - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
JF - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
IS - 4
ER -