COPZ1

COPZ1, or coatomer protein complex subunit zeta-1, is a gene that encodes one subunit of the coatomer protein complex I (COPI). COPI is involved in vesicular transport within the Golgi apparatus and in retrograde transport from the Golgi back to the endoplasmic reticulum (ER). COPI vesicles are formed on membranes through the action of ARF1, a small GTPase, and the seven subunits assemble to shape vesicles and select cargo for transport. COPZ1 is one of two zeta subunits in vertebrates, with COPZ2 acting as a paralog that can partially compensate for COPZ1 in some contexts. The zeta-1 subunit contributes to the structural integrity of the complex and to cargo selection during vesicle budding.

COPZ1 is predominantly cytosolic but associates with Golgi membranes as part of the coatomer complex. It interacts with the other COPI subunits—alpha-, beta-, beta′-, gamma-, delta-, and epsilon-COP—as well as with ARF1 during coat assembly. This network supports the recruitment of COPI to membranes and the formation of vesicles that mediate retrieval and recycling of resident proteins within the Golgi-ER axis.

Clinical significance: COPZ1 is considered essential for proper COPI coat formation and Golgi function. In experimental systems, loss or reduction of COPZ1 impairs COPI assembly, disrupts Golgi morphology, and perturbs retrograde trafficking, underscoring its critical role in intracellular transport. Specific human diseases directly caused by COPZ1 mutations have not been definitively established, though research continues to explore its role in cellular homeostasis and disease contexts.