Biology Reference
In-Depth Information
Chapter 9
NEARFIELD SCANNING OPTICAL
MICROSCOPY OF BIOLOGICAL
MEMBRANES
Thomas S. van Zanten
a
and Maria F. Garcia-Parajo
a,b
a
Single Molecule BioNanophotonics group, IBEC-Institute for Bioengineering of Catalonia
and CIBER-bbn, Baldiri Reixac 15-21, 08028 Barcelona, Spain
b
ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
mgarcia@pcb.ub.es
9.1 A VIEW ON CELL MEMBRANE COMPARTMENTALIZATION
One of the most fascinating but also controversial ields in cell biology
concerns the organization of the cellular plasma membrane. In fact, the view
of the cell membrane as a two-dimensional homogeneous structure has
changed radically in recent years by demonstrations of lateral heterogeneities,
patches and the existence of protein domains in the membrane.
1-3
The
general consensus points to a direct relation between the lateral organization
of proteins and lipids and their speciic cellular function.
4-7
Similarly, a large
body of evidence indicates that the size of many of these membrane domains
is in the range of 30 to 800 nm.
6,8
However, other workers in the ield have
seriously questioned the existence of some membrane domains in living
cells, in particular those known as membrane “rafts”.
9
Part of the controversy
regarding the existence of membrane domains lays in their physical size, being
smaller than the diffraction limit of light, and thus not resolvable by classical
optical means. Moreover, there is increasing evidence that the assembly
and disassembly of such complexes are rather dynamic and thus dificult to
visualize using standard optical microscopy settings.
10
Finally, biochemical
and biophysical approaches aimed at the study of protein domains have lead
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