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© The Rockefeller University Press,
0021-9525/1999//743 $5.00
The Journal of Cell Biology, Volume 147, Number 4,
, 1999 743-760
Original Article |
Rab6 Coordinates a Novel Golgi to ER Retrograde Transport Pathway in Live Cells
jwhite{at}embl-heidelberg.de
We visualized a fluorescent-protein (FP) fusion to Rab6, a Golgi-associated GTPase, in conjunction with fluorescent secretory pathway markers. FP-Rab6 defined highly dynamic transport carriers (TCs) translocating from the Golgi to the cell periphery. FP-Rab6 TCs specifically accumulated a retrograde cargo, the wild-type Shiga toxin B-fragment (STB), during STB transport from the Golgi to the endoplasmic reticulum (ER). FP-Rab6 TCs associated intimately with the ER, and STB entered the ER via specialized peripheral regions that accumulated FP-Rab6. Microinjection of antibodies that block coatomer protein I (COPI) function inhibited trafficking of a KDEL-receptor FP-fusion, but not FP-Rab6. Additionally, markers of COPI-dependent recycling were excluded from FP-Rab6/STB TCs. Overexpression of Rab6:GDP (T27N mutant) using T7 vaccinia inhibited toxicity of Shiga holotoxin, but did not alter STB transport to the Golgi or Golgi morphology. Taken together, our results indicate Rab6 regulates a novel Golgi to ER transport pathway.
Key Words: intracellular transport Shiga toxin Rab6 protein KDEL receptor green fluorescent protein
© 1999 The Rockefeller University Press
The online version of this article contains supplemental material.Drs. Goud and Stelzer are principal investigators.
Drs. White and Johannes contributed equally.
Dr. Reinsch's present address is Gravitational Research Branch, NASA Ames Research Center, M/S 239-11, Moffett Field, CA 94035-1000.
. Abbreviations used in this paper: CFP, cyan fluorescent protein; CLSM, confocal laser scanning microscopy; COP, coatomer protein; CT, Cholera toxin; ER, endoplasmic reticulum; GFP, green fluorescent protein; KDELR, KDEL-receptor; PE, Pseudomonas exotoxin A; ST, Shiga toxin; STB, Shiga toxin B-fragment; TCs, transport carriers; YFP, yellow fluorescent protein.
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