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. Author manuscript; available in PMC: 2009 Dec 21.
Published in final edited form as: Drug Discov Today. 2009 Sep 3;14(23-24):1130–1135. doi: 10.1016/j.drudis.2009.08.006

FIGURE 2.

FIGURE 2

Illustration of a membrane protein (KcsA, shown in purple) embedded in a lipid bilayer. For clarity, the water molecules on either side of the lipid bilayer have not been included. The hydrocarbon core of a membrane is typically ~25–30 Å wide with the headgroups spanning ~10 Å. The polar head groups of the lipids face the aqueous environment on both sides of the membrane, whereas their hydrophobic chains form the insulating interior of the bilayer. Owing to the ester carbonyls and water associated to the lipid headgroups, lipid molecules possess electrical dipoles, which result in a considerable electrical potential (positive inside the bilayer). Figure generated using KcsA crystal structure, PDB: 1K4C.