Lipid Raft

Lipid rafts called cholesterol-rich microdomains in cell membranes. 1988 presented Kai Simons in Germany and Gerrit van Meer in the Netherlands, a concept of microdomains in lipid membranes before, in which cholesterol, glycolipids and sphingolipids accumulate. They called these domains " lipid rafts ", as they like rafts floating on the two-dimensional fluid lipid membrane.

Lipid rafts, organize themselves as liquid-crystalline phase ( section). Your observation is difficult due to their small size ( close to the resolving power of classical light microscopes ), but fluorescence microscopy offers a way to make them visible. Be used, for example, dyes that intercalate between the domains as Laurdan or kopfgelabelte dyes such as Texas Red, the preference store due to their size in the disordered phase.

Properties of lipid rafts

Although the exact model is unknown, the lipid rafts minimize the free energy between the two phases - are formed domains of a typical size that neither mingle, further merge. Good observable is this separation between the "Liquid Ordered Phase" ( minor phase, L0 ) and the "Liquid Disordered Phase" " ( disordered phase Ld or L? ).

Criticism of the lipid raft concept

Although lipid rafts can be observed in the fluorescence microscope in model membranes whose evidence has not yet succeeded in living cells. About the average size ( 1-1000 nm) and life prevails among researchers so far also no consensus. It is also generally unclear whether lipid rafts exist.