Cell membrane is an organelle composed of double layer of amphipatic lipids along
with proteins. Its function is to separate the outside environment from the cell
cytoplasm. Cell membrane is a semipermeable barrier through which a selective
transport of molecules occurs. It also prevents the entry of molecules that would harm
the cell, and allows excretion of cellular waste products. Membrane lipids are laterally
segregated and this induces the formation of membrane domains with different
organisation, dynamic and function. Domains enriched with sphingolipids and
cholesterol are called membrane rafts. Rafts have nano to micrometric dimensions and
are highly dynamic, so it is quite hard to study them through conventional methods, for
example using the microscope. Currently, there is an intensive process of searching for
protein markers that would specifically bind to membrane raft components
(sphingomyelin, cholesterol, or a complex of both). Using such marker, we could have
a closer look into the function and composition of membrane rafts.
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