Theory on the structure and stability of coated vesicles.

Coated vesicles, which are found in many eucaryotic cells, seem to play a role in the transfer of membrane and in the uptake and secretion of proteins. They have polyhedral structures whose faces consist of twelve pentagons and a variable number of hexagons and at whose vertices always three edges meet. To study the stability of such structures theoretically I first enumerate all the topologically distinct polyhedra under the conditions that they have at most ten hexagonal faces. Then I estimate their strain energy assuming Hookean elasticity and considering only interactions of short range. The results show that the three structures of coated vesicles which Crowther et al. (1976) reported have the lowest energy among all the polyhedra under certain conditions. Thus, the seemingly complex structures of coated vesicles can be constructed from only one species of structural units according to the principle of lowest strain energy.