CYTOSOLIC ARFS ARE REQUIRED FOR VESICLE FORMATION BUT NOT FOR CELL-FREE INTRA-GOLGI TRANSPORT - EVIDENCE FOR COATED VESICLE-INDEPENDENT TRANSPORT

We investigated the role of ADP-ribosylation factors (ARFs) in Golgi f unction using biochemical and morphological cell-free assays. An ARF-f ree cytosol produced from soluble Chinese hamster ovary (CHO) extracts supports intra-Golgi transport by a mechanism that is biochemically i ndistinguishable from control transport reactions: ARF-free transport reactions are NSF-dependent, remain sensitive to the donor Golgi-speci fic inhibitor ilimaquinone, and exhibit kinetics that are identical to that of control reactions containing ARFs. In contrast, ARF-free cyto sol does not support the formation of coated vesicles on Golgi cistern ae. However, vesicle formation is reconstituted upon the addition of A RF1. These data suggest that neither soluble ARFs nor coated vesicle f ormation are essential for transport. We conclude that cell-free intra -Golgi transport proceeds via a coated vesicle-independent mechanism r egardless of vesicle formation on Golgi cisternae.