It was previously noted that COPII vesicles produced in vitro have a similar appearance and diameter as native ones8. By keeping sample manipulation minimal, we have now been able to observe extended constricted tubules in vitro (Fig. 3a–h) and found that they exhibit strikingly similar shapes and diameters to those seen in cells (Fig. 3i, ref. 141516). In cells, single vesicles, “dumb-bell shapes”, “tubular membranes with vesicular-shaped endings”16 and short “beaded necklaces”15 have been observed. Networks of longer vesicle strings with occasional branches were reported when GTP hydrolysis was blocked by the Sar1(H79G) mutation. This led to the suggestion that “budding continues in the absence of GTP hydrolysis, but […] vesicles fail to complete separation from one another.”15