Phase separation of phospholipid vesicles occurs in the laboratory and can be visualized by fluorescence microscopy, providing insight into the physics of phase transitions in confined geometries.  The biological importance of these processes is thought to arise from the possibility that micro-separation in the membranes of cells clusters receptors and alters local curvature in ways important to trafficking and signaling.  The past decade has seen a dramatic increase in the study of these behaviors yet almost without exception, there is no control over the membrane tension or, the membranes are at low tension.  Cell membranes on the other hand, are subject to tension from their connection (through proteins) to the underlying cytoskeleton and through external point contacts.  We demonstrate here, that mixed membranes subject to modest tensions exhibit strikingly different phase separation than is seen at low tension.  Not only can one detect a shifting of the phase transition temperature, but the type of domains observed is dramatically tension dependent.  Beautiful flower shapes, ordered hexagons, and stripes can all be observed for different tensions and cooling histories.  Our work presents a possible mechanism by which tension influences the type of phase separation and the resulting domain shape.

Influence of tension on phase separation and domain shape in phospholipid vesicles

243rd National Meeting (2012)

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