From rafts to crafts: membrane asymmetry in moving cells.

Many important biological events, including the leukocyte-mediated immune response, wound repair, axon guidance and developmental patterning, involve persistent cell movement towards a directional signal, a process termed chemotaxis. Establishment of functional and spatial cell polarity is an absolute requirement for this response. We propose that redistribution of specific membrane microdomains, termed rafts, during cell migration is a pivotal step in achieving polarity. On the one hand, partitioning of molecules into rafts might help to localize proteins at the front or the rear of moving cells, and on the other hand, rafts might function as platforms for local activation and coordination of the signaling pathways involved in cell migration.