On the role of assembly kinetics in determining the structure of clathrin cages.

The process of clathrin self-assembly into closed shells with the Fullerene structure is investigated. It is argued that the shell size distribution is governed by the kinetics of assembly and depends on the rate of growth controlled by the free clathrin concentration. The particularly abundant small structures--the "tennis ball" and the "hexagonal barrel"--are found to have a certain unique property that makes them ubiquitous in the process of slow growth. A thermal ratchet-type mechanism of the coated vesicle assembly on the membrane is proposed, and possible experimental tests are suggested.