(a) Potential roles of lipid rafts in vesicular transport. Rafts may operate as platforms for the inclusion of sorting receptors as well as cargo molecules (yellow) to the forming vesicle (1) (as exemplified in 45., 46., 47., 48. and 49•.), as sites for organizing membrane-cytoskeleton (green) complexes (2) 51., 52•. and 54••., or as sites for organizing the vesicle docking and fusion machinery (3) 94. and 95. Lipids within rafts are indicated as red and outside rafts as blue. (b) Schematic illustration of raft clustering during vesicle formation. Individual small rafts (red) may become clustered upon stimuli originating from both the cytosolic and luminal side of the membrane (e.g. receptor–ligand interactions, protein multimerization) and leading to vesicle budding. The lipid composition may contribute to the formation of membrane curvature. The putative inner membrane leaflet of a clustered raft is shown as yellow. The size and number of rafts, including potential raft subtypes within a vesicle remain to be established. Hypothetical trajectories of two proteins (green and blue lines) with affinity for rafts are shown. The clustering of individual small rafts may be accompanied by increased residency time of individual components within the same ‘super’ raft and thereby enhance the probability of interactions between raft proteins (taken form: Ikonen E (2001) Roles of lipid rafts in membrane transport. Current Opinion in Cell Biology 13(4):470 - 477. )
Mediante el marcaje de la membrana con lípidos fluorescente sintéticos, es posible monitorear el movimiento de los microdominios, de la membranas.
En estas imágenes se trazan las trayectorias registradas por un tipo de mirodominios denominados balsas lipídicas, muy prevalentes en las membranas plasmáticas de células animales.
La evidencia indica que las proteínas asociadas a los microdominios, se desplazan juntas sobre la superficie membranal, lo cual permite conjuntar grupos de proteínas, que actúan en armonía en algún proceso, para hacer más rápida y eficiente su acción.