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Nature. 1996 Dec 5;384(6608):479-81.

Nucleotide exchange on ARF mediated by yeast Gea1 protein.

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Service de Biochimie et Génétique Moléculaire, Département de Biologie Cellulaire et Moléculaire, CEA/Saclay, Gif-sur-Yvette, France.


The ADP-ribosylation factor ARF is a small GTP-binding protein that is involved in the transport of vesicles between the endoplasmic reticulum (ER) and Golgi complex and within the Golgi complex itself. ARF cycles between inactive and membrane-associated active forms as a result of exchange of bound GDP for GTP; the GTP-bound form is an essential participant in the formation of transport vesicles. This nucleotide exchange is inhibited by the fungal metabolite brefeldin A (BFA). Here we identify a protein (Gea1) from Saccharomyces cerevisiae that is a component of a complex possessing guanine-nucleotide-exchange activity for ARF. We show that the activity of the complex is sensitive to brefeldin A and that Gea1 function is necessary for ER-Golgi transport in vivo. Gea1 contains a domain that is similar to a domain of Sec7, a protein necessary for intra-Golgi transport. We propose that Gea1 and ARNO, a human protein with a homologous Sec7 domain, are members of a new family of ARF guanine-nucleotide exchange factors.

[Indexed for MEDLINE]

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