Mapping the faces of mitochondria and ER

APEX2 proximity biotinylation yields high-quality proteomic maps of cytosol-facing outer mitochondrial and ER membranes in living human cells.

Source

Proteomic mapping of cytosol-facing outer mitochondrial and ER membranes in living human cells by proximity biotinylation

Hung V, Lam SS, Udeshi ND, et al. · eLife · 2017

What they did

Used APEX2 proximity labeling in living cells to define proteins on the OMM and ER membrane facing the cytosol.

Maps capture expected functional classes and enrich many additional proteins (22 OMM; 72 ERM), providing resources beyond classical fractionation.

The limits

A proteomic inventory is not a full functional validation of every newly enriched protein.

Key terms

APEX2: Engineered peroxidase for proximity biotinylation proteomics.
OMM: Outer mitochondrial membrane.
ERM: Endoplasmic reticulum membrane.
Proximity biotinylation: Labeling proteins near an enzyme tag in living cells.
Sub-organellar proteome: Protein inventory of a membrane/compartment face.

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Method:

Common questions

Method?

APEX2 proximity biotinylation.

Membranes mapped?

Cytosol-facing OMM and ERM.

Extra enrichments reported?

22 OMM and 72 ERM classes/proteins noted.

Prior approach?

Biochemical fractionation.