COP1 Coated Vesicles and ARF Protein

COP1 Coated Vesicles

• Used for:

  • Transporting substances from the Golgi back to the ER.

  • Moving substances between different Golgi cisternae.

ARF Protein

• Initiates the COP1 process.

• Stands for ADP ribosylation factor.

• Binds to GDP (Guanosine diphosphate) initially.

  • In this state, ARF cannot interact with the membrane.

Guanine Nucleotide Exchange Factor (GNEF)

• Converts GDP to GTP (Guanosine triphosphate) on ARF.

• This conversion induces a conformational change in ARF.

• ARF can now interact with the membrane.

COP1 Binding

• ARF interacts with the membrane and binds COP1.

• COP1 binding leads to the invagination or formation of the vesicle.

• COP1 alone is sufficient for vesicle formation; no additional factors are needed for pinching off.

Coat Protein Detachment

• To detach the coat proteins, ARF hydrolyzes GTP back to GDP.

• ARF-GDP can no longer interact with the membrane, causing the coat proteins to fall off.

• Released coat proteins are recycled for future vesicle formation.

Vesicle Destination

• The vesicle can then be transported to its target location.

  • Either the ER.

  • Or a different Golgi cisterna.