thecoatomer
The coatomer is a protein complex involved in vesicular transport within eukaryotic cells. It plays a crucial role in the retrograde transport pathway, moving proteins from the Golgi apparatus back to the endoplasmic reticulum (ER). This process is essential for maintaining the correct localization of ER-resident proteins, which may have inadvertently escaped to the Golgi during their synthesis and initial trafficking.
The coatomer is composed of seven different subunits: $\alpha$, $\beta$, $\beta'$, $\gamma$, $\delta$, $\epsilon$, and $\zeta$.
When ARF proteins are in their GTP-bound form, they promote the recruitment of coatomer to the Golgi
Once the COPI-coated vesicle reaches the ER, the GTPase-activating protein (GAP) activity of the ER membrane