Atg8 transferases catalyse the transfer of the ubiquitin-like protein Atg8 from one substrate to another. Analogous to ubiquitination, Atg8 is first activated by the E1-like enzyme Atg7, and is then transferred to the E2-like enzyme Atg3. In the final step, the E3-like Atg5-Atg12 heterodimer acts to conjugate Atg8 to phosphatidylethanolamine in a membrane-associated form. Atg8 transferase activity is required for autophagosome biogenesis. (Adapted from PMID:18704115.)