To investigate this possibility and avoid centrifugation, we replaced the 400 nm liposomes by Giant Unilamellar Vesicles (GUVs), which allows direct visualization by confocal microscopy. No manipulation was required after initial mixing of COPII proteins and GUVs. In addition, electron microscopy (EM) was performed using negative stain and cryo-EM. GUVs were found to be suitable for cryo-EM preparations and superior to Large Unilamellar Vesicles (LUVs), because of larger membrane reservoirs and higher unilamellarity.