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  • Cargo-selective SNX-BAR proteins mediate retromer trimer independent retrograde transport.

Cargo-selective SNX-BAR proteins mediate retromer trimer independent retrograde transport.

The Journal of cell biology (2017-09-25)
Arunas Kvainickas, Ana Jimenez-Orgaz, Heike Nägele, Zehan Hu, Jörn Dengjel, Florian Steinberg
ABSTRACT

The retromer complex, which recycles the cation-independent mannose 6-phosphate receptor (CI-MPR) from endosomes to the trans-Golgi network (TGN), is thought to consist of a cargo-selective VPS26-VPS29-VPS35 trimer and a membrane-deforming subunit of sorting nexin (SNX)-Bin, Amphyphysin, and Rvs (BAR; SNX-BAR) proteins. In this study, we demonstrate that heterodimers of the SNX-BAR proteins, SNX1, SNX2, SNX5, and SNX6, are the cargo-selective elements that mediate the retrograde transport of CI-MPR from endosomes to the TGN independently of the core retromer trimer. Using quantitative proteomics, we also identify the IGF1R, among more potential cargo, as another SNX5 and SNX6 binding receptor that recycles through SNX-BAR heterodimers, but not via the retromer trimer, in a ligand- and activation-dependent manner. Overall, our data redefine the mechanics of retromer-based sorting and call into question whether retromer indeed functions as a complex of SNX-BAR proteins and the VPS26-VPS29-VPS35 trimer.

MATERIALS
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Brand
Product Description

Sigma-Aldrich
Monoclonal Anti-SNX6 antibody produced in mouse, clone SNX6-76, ascites fluid, buffered aqueous solution