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Quantitative Localization of a Golgi Protein by Imaging Its Center of Fluorescence Mass
Published on: August 10, 2017
Rab6 coordinates a novel Golgi to ER retrograde transport pathway in live cells
J White1, L Johannes, F Mallard
1Light Microscopy Group, European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany. jwhite@embl-heidelberg.de
The Journal of Cell Biology
|November 24, 1999
Summary
Rab6 regulates a new transport pathway from the Golgi to the endoplasmic reticulum (ER). This pathway moves Shiga toxin B-fragment (STB) retrograde cargo, distinct from COPI-dependent recycling.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Trafficking
Background:
- The secretory pathway involves complex protein transport within eukaryotic cells.
- Rab GTPases are key regulators of intracellular membrane trafficking.
- The Shiga toxin B-fragment (STB) is a well-characterized retrograde cargo.
Purpose of the Study:
- To investigate the role of Rab6 in intracellular transport.
- To identify novel transport pathways regulated by Rab6.
- To elucidate the mechanism of Shiga toxin B-fragment (STB) retrograde transport.
Main Methods:
- Fluorescent protein (FP) tagging of Rab6 and secretory pathway markers.
- Live-cell imaging of transport carriers (TCs).
- Immunological assays to block coatomer protein I (COPI) function.
- Overexpression of Rab6 mutants.
Main Results:
- FP-Rab6 labeled dynamic TCs moving from the Golgi to the cell periphery.
- These FP-Rab6 TCs specifically accumulated STB during Golgi-to-ER transport.
- STB entered the ER via Rab6-accumulating peripheral regions.
- COPI-dependent trafficking was unaffected by FP-Rab6, and COPI markers were excluded from FP-Rab6/STB TCs.
- Rab6:GDP (T27N mutant) overexpression inhibited Shiga holotoxin toxicity without affecting STB Golgi transport.
Conclusions:
- Rab6 regulates a novel, COPI-independent transport pathway from the Golgi to the ER.
- This pathway is involved in the retrograde transport of STB.
- Rab6 plays a critical role in directing specific cargo, like STB, to the ER.
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