Biology Reference
In-Depth Information
Chapter 6
NANOPHYSIOLOGY OF CELLS, CHANNELS
AND NUCLEAR PORES
Hermann Schillers, Hans Oberleithner and Victor Shahin
Institute of Physiology II, Medical Department, University of Münster,
Robert-Koch Street 27b, D-48149 Münster, Germany
shahin@uni-muenster.de
6.1
PLASMA MEMBRANE
6.1.1
Plasma Membrane and Channels
The plasma membrane separates the cell interior from the extracellular space
by using a lipid bilayer. This lipid bilayer accommodates diverse membrane
proteins, including integral membrane proteins such as receptors, ion
channels and transporters, as well as certain antigens that are peripherally
associated with the membrane. Because of their important roles in cell
growth, differentiation and cell-cell signalling, the structures of the plasma
membrane and the proteins associated with it have attracted wide attention
and have been extensively investigated.
Several techniques are available to investigate the heterogeneity
of cell membranes, but they show limitations in terms of resolution or
artiicial conditions. For biochemical approaches, membranes are usually
fractionalized, and therefore the arrangement of proteins and membrane
domains is hardly observable at the scale of a cell. Atomic force microscopy
(AFM) is a surface probe that visualizes protein structures at nanometre
range in native membranes without using ixatives. This allows protein
counting and protein height measurements essential for the determination
of individual molecular masses and protein distribution on the cell surface.
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