A ubiquitin-like protein involved in membrane fusion.

Atg8 is a ubiquitin-like protein involved in autophagy in yeast that is targeted to membranes through conjugation to the lipid phosphatidylethanolamine (PE). In this issue of Cell, Nakatogawa et al. (2007) show that Atg8 conjugated to PE mediates tethering between adjacent membranes and stimulates membrane hemifusion, an event that may mimic expansion of the autophagosomal membrane during autophagy.