ADP-ribosylation factor 1 dependent clathrin-coat assembly on synthetic liposomes.
The assembly of clathrin-coated vesicles on Golgi membranes is initiated by the GTP-binding protein ADP ribosylation factor (ARF), which generates high-affinity membrane-binding sites for the heterotetrameric AP-1 adaptor complex. Once bound, the AP-1 recruits clathrin triskelia, which polymerize to form the coat. We have found that ARF.GTP also recruits AP-1 and clathrin onto protein-free liposomes. The efficiency of this process is modulated by the composition of the liposomes, with phosphatidylserine being the most stimulatory phospholipid. There is also a requirement for cytosolic factor(s) other than ARF. Thin-section electron microscopy shows the presence of clathrin-coated buds and vesicles that resemble those formed in vivo. These results indicate that AP-1-containing clathrin-coated vesicles can form in the absence of integral membrane proteins. Thus, ARF.GTP, appropriate lipids, and cytosolic factor(s) are the minimal components necessary for AP-1 clathrin-coat assembly.
Zhu
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Y
Washington University School of Medicine, Department of Internal Medicine, 660 South Euclid Avenue, Box 8125, St. Louis, MO 63110, USA.
Drake
M T
MT
Kornfeld
S
S
D020727:ADP-Ribosylation Factors; D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D001692:Biological Transport; D018699:Coated Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure*; D008081:Liposomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008854:Microscopy, Electron
D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D008081:Liposomes; D008565:Membrane Proteins; D019204:GTP-Binding Proteins; D020727:ADP-Ribosylation Factors