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New COP1-binding motifs involved in ER retrieval
P Cosson1, Y Lefkir, C Démollière
1Centre Médical Universitaire, Département de Morphologie, Genève, Switzerland.
The EMBO Journal
|December 8, 1998
Summary
Researchers identified a new protein sequence, deltaL, that binds to the COP1 complex, mediating protein retrieval from the Golgi to the endoplasmic reticulum (ER). This discovery highlights COP1
Area of Science:
- Cell biology
- Molecular biology
- Protein trafficking
Background:
- Coatomer protein complex (COP1) mediates protein sorting via interactions with targeting motifs.
- COP1 binding to dilysine (KKXX) motifs retrieves proteins from the Golgi to the endoplasmic reticulum (ER).
Purpose of the Study:
- To characterize a novel sequence (deltaL) that interacts with the COP1 complex.
- To investigate the role of deltaL in protein localization and retrograde transport.
Main Methods:
- Yeast two-hybrid system to identify deltaL interaction with COP1.
- Mutagenesis studies to determine critical residues for deltaL-COP1 binding.
- Reporter protein localization assays in yeast and mammalian cells.
Main Results:
- The deltaL sequence specifically interacts with the delta-COP subunit of COP1.
- Transferring deltaL to a reporter protein caused its ER localization due to Golgi-to-ER retrieval.
- An aromatic residue within deltaL is critical for COP1 interaction.
- Similar COP1-binding motifs with essential aromatic residues were found in Sec71p and CD3epsilon.
Conclusions:
- The COP1 complex plays a crucial role in retrograde transport from the Golgi to the ER.
- The deltaL motif represents a novel COP1-binding motif involved in ER retrieval.
- COP1-mediated retrograde transport shares functional similarities with clathrin-adaptor complexes.