Modeling distinct compartments

Heinrich and Rapoport (page 271) have used mathematical modeling to generate the first explanation of how a bidirectional transport system can generate unique compartments, such as the ER and Golgi, despite constant vesicle movement between them. The model provides testable predictions about the vesicle transport system in cells.In modeling a two-organelle system, the team found that they only needed to include two molecular components of the vesicle transport system: the coat proteins for budding; and the SNARE proteins for fusion. Coat proteins regulate budding from distinct compartments: COPI from the Golgi (to the ER); and COPII from the ER (to the Golgi). Meanwhile, SNARE proteins work in pairs, with a v-SNARE localized in the vesicle membrane and the t-SNARE in the target membrane. Different SNAREs direct vesicle fusion to specific organelles.

The...