Autophagy is a process of intracellular bulk degradation in which cytoplasmic components including organelles are sequestered within double-membrane vesicles that deliver the contents to the lysosome/vacuole for degradation. LC3, GABARAP (-aminobutyric-acid-type-A-receptor-associated protein), and GATE-16 (Golgi-associated ATPase enhancer of 16 kDa) have been identified as a homologue of yeast Atg8. These homologues have been characterized as modifiers in reactions mediated by hAtg7 (an E1-like enzyme) and hAtg3 (an E2-like enzyme) as in yeast Atg8 lipidation. These homologues also generate form II, which are recovered in membrane fractions. Generation of the form II correlates with autophagosome association. These results suggest that all mammalian Atg8 homologues receive a common modification to associate with autophagosomal membrane as the form II.