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Intrinsic curvature hypothesis for biomembrane lipid composition: a role for nonbilayer lipids

Journal Article · · Proc. Natl. Acad. Sci. U.S.A.; (United States)
A rationale is presented for the mix of bilayer and nonbilayer lipids, which occurs in biomembranes. A theory for the L/sub /-H/sub II/ phase transition and experimental tests of the theory are reviewed. It is suggested that the phase behavior is largely the result of a competition between the tendency for certain lipid monolayers to curl and the hydrocarbon packing strains that result. The tendency to curl is quantitatively given by the intrinsic radius curvature, R/sub o/, which minimizes the bending energy of a lipid monolayer. When bilayer (large R/sub o/) and nonbilayer (small R/sub o/) lipids are properly mixed, the resulting layer has a value of R/sub o/ that is at the critical edge of bilayer stability. In this case, bilayers may be destabilized by the protein-mediated introduction of hydrophobic molecules, such as dolichol. An x-ray diffraction investigation of the effect of dolichol on such a lipid mixture is described. This leads to the hypothesis that biomembranes homeostatically adjust their intrinsic curvatures to fall into an optimum range. Experimental strategies for testing the hypothesis are outlined.
Research Organization:
Princeton Univ., NJ
DOE Contract Number:
AC02-76EV03120
OSTI ID:
6333688
Journal Information:
Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 82:11; ISSN PNASA
Country of Publication:
United States
Language:
English