Mammalian Cdc42 is a brefeldin A-sensitive component of the Golgi apparatus.
In this study, we have used immunocytochemical and fractionation approaches to provide a description of the localization of the mammalian Cdc42 protein (designated Cdc42Hs) in vivo. A specific anti-peptide antibody was generated against the C-terminal region of Cdc42Hs. Using affinity-purified preparations of this antibody in indirect immunofluorescence experiments, Cdc42Hs was found to be localized to the Golgi apparatus. Similar to the well-characterized non-clathrin coat proteins ADP-ribosylation factor (ARF) and beta-COP, the perinuclear clustering of Cdc42Hs is rapidly dispersed upon exposure of the cells to the drug brefeldin A, suggesting that it too may play a role in the processes of intracellular lipid and protein transport. Employing cell lines possessing inducible forms of ARF, we demonstrate here a tight coupling of the nucleotide-bound state of ARF and the subcellular localization of Cdc42Hs. Specifically, the expression of wild-type ARF had no effect on the brefeldin A sensitivity of Cdc42Hs while, as is the case for ARF and beta-COP, expression of a GTPase-deficient form of ARF (ARF(Q71L)) renders these Golgi-localized proteins resistant to brefeldin A treatment (; ). Moreover, the induced expression of a mutant form of ARF with a low affinity for nucleotide resulted in constitutive redistribution of Cdc42Hs in the absence of brefeldin A treatment. These results suggest that Cdc42Hs may play a role in cell morphogenesis by acting on targets in the Golgi that direct polarized growth at the plasma membrane.
Department of Pharmacology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, USA.
J W
JW
Erickson
C j
Cj
Zhang
R A
RA
Kahn
T
T
Evans
R A
RA
Cerione
D000818:Animals; D020126:Brefeldin A; D018797:Cell Cycle Proteins / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000187:drug effects* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D011817:Rabbits; D020764:cdc42 GTP-Binding Protein
D018797:Cell Cycle Proteins; D003517:Cyclopentanes; D020126:Brefeldin A; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein