STRUCTURE AND INTRACELLULAR-LOCALIZATION OF MOUSE ADP-RIBOSYLATION FACTORS TYPE-1 TO TYPE-6 (ARF1-ARF6)

ADP-ribosylation factors (ARFs) are a family of small GTP-binding prot eins that are proposed to be involved in the formation of coated trans port vesicles. Although six ARF sequences have been reported in mammal s to date, it has been unclear how many ARF members are present in a s ingle organism. In this study, we provide the first direct evidence by cDNA cloning for the presence of all six ARF members in mouse. These proteins are highly conserved across mammalian species and Northern bl ot analysis revealed that mRNAs for all the members mere expressed ubi quitously. Transfection of cells with epitope-tagged ARFs revealed tha t ARFs 1-3 displayed a perinuclear Golgi localization, while ARFs 4-6 appeared to be widely dispersed throughout the cytoplasm. These result s suggest that although all the ARF proteins play fundamental and crit ical roles in cellular function, they are involved in different vesicu lar transport processes.