Table I.

Effects of human TBC domain–containing proteins on Shiga toxin transport

Rab GAPWild-type TBC domainCatalytically inactive TBC domain
Target
 RabSTxBGAP
 localizationEGFGolgiSTxBGAP
 localizationEGF
EVI-535VesicularCytosolicEarly
 endosomesaIntactGolgiTubules,
 cytosolicND
RN-tre
     (USP6NL)41Cell surface
 vesicularCell surfaceEarly
 endosomesaFragmentedGolgiCell surfaceND
RabGAP-5
     (RUTBC3)5A-CGolgiCytosolicCell surfaceIntactGolgibCytosolicEarly
 endosomes
TBC1D10ANDVesicular
 GolgiCell surfaceEarly
 endosomesaIntactGolgiCell surfaceND
TBC1D10B22a/31VesicularCell surfaceEarly
 endosomesIntactGolgiCell surfaceND
TBC1D10CNDVesicularFilopodia,
 cell surfaceEarly
 endosomesIntactGolgiCell surfaceND
TBC1D11
     (GAPCenA)4>11GolgiCytosolicEarly
 endosomesIntactNDCytosolicND
TBC1D14NDRecycling
 endosomesRecycling
 endosomesEarly
 endosomesFragmentedRecycling
 endosomesRecycling
 endosomesND
TBC1D1721VesicularCytosolicEarly
 endosomesIntactGolgiCytosolicND
TBC1D22A33A-BcGolgi
 fragmentsCytosolic,
 nuclearEarly
 endosomesFragmentedGolgiCytosolic/
 nuclearND
TBC1D22B33A-BcGolgi
 fragmentsCytosolic,
 nuclearEarly
 endosomesFragmentedGolgiCytosolic/
 nuclearND
  • HeLa cells were transfected for 24 h with GFP-tagged wild-type or catalytically inactive Rab GAPs. These cells were then used for SSTxB or EGF uptake assays, and the uptake of STxB and EGF were scored at 1 h or 30 min, respectively. A 0-min time point was also taken to verify that both STxB and EGF were bound to the cell surface with equal efficiency for all conditions. Localization of the GFP-tagged Rab GAPs was also scored.

  • a Some highly expressing cells failed to bind EGF at the zero time point, indicating a potential defect in the trafficking of EGF receptor to the cell surface. However, the majority of cells bound and took up EGF as normal.

  • b The RabGAP-5 GAP domain was used for this experiment.

  • c TBC1D22 family GAPs have previously been shown to act on Rab33 (Pan et al., 2006).