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.
Erickson
J W
JW
Department of Pharmacology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, USA.
Zhang
C j
Cj
Kahn
R A
RA
Evans
T
T
Cerione
R A
RA
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