Comparative activity of ADP-ribosylation factor family members in the early steps of coated vesicle formation on rat liver Golgi membranes.
We have compared the abilities of mammalian ADP-ribosylation factors (ARFs) 1, 5, and 6 and Saccharomyces cerevisiae ARF2 to serve as substrates for the rat liver Golgi membrane guanine nucleotide exchange factor and to initiate the formation of clathrin- and coatomer protein (COP) I-coated vesicles on these membranes. While Golgi membranes stimulated the exchange of GTPgammaS for GDP on all of the ARFs tested, mammalian ARF1 was the best substrate, with an apparent Km of 5 microM. In all cases myristoylation of ARF was required for stimulation. Agents that inhibit the Golgi membrane guanine nucleotide exchange factor (the fungal metabolite brefeldin A and trypsin treatment) selectively inhibited the guanine nucleotide exchange on mammalian ARF1. Taken together, these data indicate that of the ARFs tested, only mammalian ARF1 is activated efficiently by the Golgi guanine nucleotide exchange factor. The other ARFs are activated mainly by another mechanism, possibly phospholipid-mediated. Once activated, all of the membrane-associated, myristoylated ARFs promoted the recruitment of coatomer to about the same extent. Mammalian ARFs 1 and 5 were the most effective in promoting the recruitment of the AP-1 adaptor complex, whereas yeast ARF2 was the least active. These data indicate that the specificity for ARF action on the Golgi membranes is primarily determined by the Golgi guanine nucleotide exchange factor, which has a strong preference for myristoylated mammalian ARF1.
Liang
J O
JO
Department of Medicine, Washington University, St. Louis, Missouri 63110, USA.
Kornfeld
S
S
D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; D000818:Animals; D020126:Brefeldin A; D018699:Coated Vesicles / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D014357:Trypsin / Q000494:pharmacology
D003517:Cyclopentanes; D006150:Guanine Nucleotides; D009227:Myristic Acids; D011994:Recombinant Proteins; D019814:Myristic Acid; D020126:Brefeldin A; D014357:Trypsin; D019204:GTP-Binding Proteins; C486434:Arf2 protein, rat; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors