Lipid polymorphism and the roles of lipids in membranes

Chem Phys Lipids. Jun-Jul 1986;40(2-4):127-44. doi: 10.1016/0009-3084(86)90067-8.

Abstract

The reasons for lipid diversity in membranes are not understood. Here we review evidence supporting the proposal that factors related to the polymorphic capabilities of lipids provide a rationale for lipid diversity. In particular, the ability of lipids to adopt different polymorphic phases appears to be related to a generalized shape property, where lipids with a cylindrical geometry preferentially adopt the bilayer phase whereas 'cone' shaped lipids adopt the hexagonal HII phase. Lipid diversity may then be considered to satisfy three demands. The first is obviously a need for bilayer forming lipids to provide the basic permeability barrier, whereas the second concerns a need for non-bilayer lipids and associated structures for fusion and related membrane contact phenomena to proceed. A third, and less obvious demand satisfied by nonbilayer lipids concerns the ability of lipids of different shapes to modulate the order in the hydrocarbon region when constrained to a bilayer organization. These possibilities are summarized in a metamorphic mosaic model of membranes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Freeze Fracturing
  • Lipid Bilayers
  • Liposomes*
  • Microscopy, Electron
  • Models, Biological*
  • Models, Molecular
  • Molecular Conformation
  • Structure-Activity Relationship

Substances

  • Lipid Bilayers
  • Liposomes