Nanotechnology-Enabled Sensors

430 Chapter 7: Organic Nanotechnology Enabled Sensors
Fig. 7.50 Helix formation and bundling/association within membranes.
There is another type of proteins which acts as transmembrane transporters.
These proteins allow nutrients, metabolites and ion to travel
across the lipid bilayers (Fig. 7.51). These proteins are necessary as the
lipid bilayers, which are the building blocks of the membrane structures,
are highly impermeable to all ions and charged molecules and many nutrients
and wastes such as sugars, amino acids, nucleotides and many cell
metabolites.
Each transport protein provides a private passageway across the membrane
for a special class of molecules. These membrane proteins extend
through the bilayer, with part of their mass on either side. They have both
hydrophobic and hydrophilic regions. The hydrophobic region is in the interior
of the bilayer which binds to the hydrophobic tails of the lipid bilayer.
The hydrophilic regions of these proteins are exposed to the aqueous
environment on either side of the membrane. It is possible to remove these
proteins from the membrane by disrupting the lipid bilayer (i.e with a detergent).