Lively Lipids Provide for Function

Abstract

It has been intensively discussed whether lipid phase transitions have any bearing on biological phenomena, and there are conflicting opinions concerning this question . The viewpoint to be advocated here is that lipid phase transitions as such are unlikely to be of direct relevance for most membrane functions. They are simply not robust enough to be of use in the delicate and specific regulation that is needed in biology. Having said this we are left with the fact that lipids in lipid membrane assemblies are social; they behave in a cooperative manner that reflects the underlying phase equilibria. This has to be reflected in the way a membrane is organized and ultimately in the manner it functions. In order to give some hints as to which effects lipid phase behavior may have on membrane function, we present two simple examples on passive membrane functions that are affected by the fluctuations accompanying bilayer phase transitions.