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Binding of ARF and beta-COP to Golgi membranes: possible regulation by a trimeric G protein
J G Donaldson1, R A Kahn, J Lippincott-Schwartz
1Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Abstract:
The binding of cytosolic coat proteins to organelles may regulate membrane structure and traffic. Evidence is presented that a small guanosine triphosphate (GTP)-binding protein, the adenosine diphosphate ribosylation factor (ARF), reversibly associates with the Golgi apparatus in an energy, GTP, and fungal metabolite brefeldin A (BFA)-sensitive manner similar to, but distinguishable from, the 110-kilodalton cytosolic coat protein beta-COP. Addition of beta gamma subunits of G proteins inhibited the association of both ARF and beta-COP with Golgi membranes that occurred upon incubation with guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S). Thus, heterotrimeric G proteins may function to regulate the assembly of coat proteins onto the Golgi membrane.