Propping Up Cholesterol

摘要

Cholesterol is a key component of mammalian cell membranes, but where does it reside? Although it is usually thought to reside "upright" with its hydroxyl group at the water interface, neutron scattering studies have found it lying near the center of the bilayer when the membranes are composed of polyunsaturated fatty acid (PUFA) chains. Kucerka et al. used neutron scattering to examine whether the lipid composition of bilayers may play a role in orienting cholesterol. They compared the impacts of adding either monounsaturated or dis-aturated lipids to PUFA bilayers containing cholesterol. Whereas adding 50% of the monounsaturated lipid moved cholesterol back to the upright position, the same effect occurred on addition of only 5% of the disaturated lipid.