Figure 1.

Major phospholipid classes of mitochondria. Chemical formulas and geometrical forms of the major mitochondrial phospholipids are shown. The shape-structure concept of lipids compares the area of the head group with the area of their acyl chains. If the cross-section area of the head group is similar to that of the acyl chains, lipids have an overall cylindrical shape and have a strong tendency of self-assembly into bilayer phases of biological membranes. A typical example for such geometry is PC. If the cross-section area of the head group is smaller than that of the acyl chains, lipids have a conical shape and form structures with negative curvature such as hexagonal phase. Examples of this type are PE and CL. While PC, PS, and PI exhibit cylindrical shape and self-organize into bilayers, PE and CL with their conical shape induce hexagonal phases and disturb bilayer arrangement.