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Updated: Apr 26, 2026
Reconstitution of Msp1 Extraction Activity with Fully Purified Components
Published on: August 10, 2021
The Get1/2 transmembrane complex is an endoplasmic-reticulum membrane protein insertase.
Fei Wang1, Charlene Chan1, Nicholas R Weir1
1Department of Molecular and Cellular Biology, Harvard University, Northwest Labs, Cambridge, Massachusetts 02138, USA.
Tail-anchored proteins insert into the endoplasmic reticulum via Get3 and Get1/2. The Get1/2 transmembrane domain actively releases proteins from Get3, facilitating insertion.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Trafficking
Background:
- Tail-anchored proteins insert post-translationally into the ER membrane via a dedicated pathway.
- The Get3 (TRC40) factor shields their transmembrane domains in the cytosol before insertion.
- The Get1/2 (WRB/CAML) complex interacts with Get3 to release substrates for insertion.
Purpose of the Study:
- To investigate the role of the Get1/2 transmembrane domain in tail-anchored protein insertion.
- To determine if Get1/2 cytosolic domains alone are sufficient for insertion.
- To elucidate the mechanism of substrate release from Get3.
Main Methods:
- Utilized cell reporters to study protein insertion.
- Employed biochemical reconstitution assays.
- Generated and analyzed mutations in the Get1/2 transmembrane domain.
Main Results:
- Mutations in the Get1/2 transmembrane domain disrupted insertion without affecting cytosolic domain function.
- These mutations revealed a novel Get1/2 insertase function.
- Substrates remained bound to Get3 when the Get1/2 insertase function was impaired, even near the ER membrane.
Conclusions:
- The Get1/2 transmembrane domain is essential for releasing tail-anchored proteins from Get3.
- Spontaneous insertion of transmembrane domains is not the mechanism; insertion is facilitated.
- A pre-integrated intermediate involving Get1/2 transmembrane domain interactions facilitates tail-anchor entry into the ER membrane.
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