Retrograde transport from the Golgi region to the endoplasmic reticulum is sensitive to GTP gamma S.
The involvement of GTP-binding proteins in the intracellular transport of the secretory glycoprotein alpha 1-antitrypsin was investigated in streptolysin O-permeabilized HepG2 cells. This permeabilization procedure allows ready access to the intracellular milieu of the membrane-impermeant, nonhydrolyzable GTP analog GTP gamma S. In streptolysin O-permeabilized HepG2 cells, the constitutive secretory pathway remains functional and is sensitive to GTP gamma S. Exposure of HepG2 cells to brefeldin A resulted in redistribution of Golgi-resident glycosyltransferases (including both alpha 2----3 and alpha 2----6 sialyltransferases) to the ER. This redistribution was sensitive to GTP gamma S. Our results suggest that GTP-binding proteins are involved in the regulation not only of the anterograde, but also of the retrograde, pathway.
Tan
A
A
The Netherlands Cancer Institute, Division of Cellular Biochemistry, Amsterdam.
Bolscher
J
J
Feltkamp
C
C
Ploegh
H
H
D001426:Bacterial Proteins; D001692:Biological Transport / Q000187:drug effects; D020126:Brefeldin A; D002463:Cell Membrane Permeability; D003517:Cyclopentanes / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D006801:Humans; D008854:Microscopy, Electron; D012794:Sialic Acids / Q000378:metabolism; D012799:Sialyltransferases / Q000378:metabolism; D013301:Streptolysins; D014407:Tumor Cells, Cultured; D000515:alpha 1-Antitrypsin / Q000378:metabolism*
D001426:Bacterial Proteins; D003517:Cyclopentanes; D012794:Sialic Acids; D013301:Streptolysins; D000515:alpha 1-Antitrypsin; C025964:streptolysin O; D020126:Brefeldin A; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D012799:Sialyltransferases