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Updated: Aug 4, 2026

Detection of Toxin Translocation into the Host Cytosol by Surface Plasmon Resonance
Published on: January 3, 2012
Retrograde transport of protein toxins under conditions of COPI dysfunction
Alice Chen1, Tonghuan Hu, Carole Mikoryak
1Molecular and Cell Biology Department, FO31, University of Texas at Dallas, Box 830688, Richardson, TX 75083-0688, USA.
Abstract:
Retrograde transport dependent on coat protein I (COPI) was impaired using two different approaches and the effects on the retrograde transport of protein toxins were investigated. One approach was to study ldlF cells that express a temperature-sensitive defect in the epsilon-COP subunit of COPI. The second approach was to treat cells with 1,3-cyclohexanebis(methylamine) (CBM), a drug that interferes with the binding of COPI to Golgi membranes. With both approaches, cells remained sensitive to a variety of protein toxins regardless of whether the toxins contained a KDEL motif. Moreover, cholera toxin, which contains a KDEL sequence, was observed by immunofluorescence microscopy to enter the endoplasmic reticulum of Vero cells in the presence of CBM. These data support published evidence indicating the presence in cells of a COPI- and KDEL receptor-independent pathway of retrograde transport from the Golgi complex to the endoplasmic reticulum. In addition, the results suggest that certain toxins containing a KDEL motif may use either the COPI-dependent or COPI-independent pathway of retrograde transport.
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