Tail-Anchored Protein Insertion by a Single Get1/2 Heterodimer

Publication date: 5 September 2017
Source:Cell Reports, Volume 20, Issue 10
Author(s): Benjamin E. Zalisko, Charlene Chan, Vladimir Denic, Ronald S. Rock, Robert J. Keenan
The Get1/2 transmembrane complex drives the insertion of tail-anchored (TA) proteins from the cytosolic chaperone Get3 into the endoplasmic reticulum membrane. Mechanistic insight into how Get1/2 coordinates this process is confounded by a lack of understanding of the basic architecture of the complex. Here, we define the oligomeric state of full-length Get1/2 in reconstituted lipid bilayers by combining single-molecule and bulk fluorescence measurements with quantitative in vitro insertion analysis. We show that a single Get1/2 heterodimer is sufficient for insertion and demonstrate that the conserved cytosolic regions of Get1 and Get2 bind asymmetrically to opposing subunits of the Get3 homodimer. Altogether, our results define a simplified model for how Get1/2 and Get3 coordinate TA protein insertion.

Graphical abstract

Teaser

Tail-anchored membrane proteins are inserted into the endoplasmic reticulum via the post-translational GET pathway. Zalisko et al. combine single-molecule and bulk fluorescence measurements with quantitative in vitro insertion assays to define the architecture of the heterodimeric Get1/2 insertase and its engagement with the soluble chaperone Get3.


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