Details

Autor(en) / Beteiligte

• Rapak, Andrzej
• Falnes, Pal O.
• Olsnes, Sjur

Titel

Retrograde Transport of Mutant Ricin to the Endoplasmic Reticulum with Subsequent Translocation to Cytosol

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 1997-04, Vol.94 (8), p.3783-3788

Ort / Verlag

United States: National Academy of Sciences of the United States of America

Erscheinungsjahr

1997

Quelle

Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals

Beschreibungen/Notizen

• Translocation of ricin A chain to the cytosol has been proposed to take place from the endoplasmic reticulum (ER), but attempts to visualize ricin in this organelle have failed. Here we modified ricin A chain to contain a tyrosine sulfation site alone or in combination with N-glycosylation sites. When reconstituted with ricin B chain and incubated with cells in the presence of Na2 35SO4, the modified A chains were labeled. The labeling was prevented by brefeldin A and ilimaquinone, and it appears to take place in the Golgi apparatus. This method allows selective labeling of ricin molecules that have already been transported retrograde to this organelle. A chain containing C-terminal N-glycosylation sites became core glycosylated, indicating retrograde transport to the ER. In part of the toxin molecules, the A chain was released from the B chain and translocated to the cytosol. The finding that glycosylated A chain was present in the cytosol indicates that translocation takes place after transport of the toxin to the ER.