In yeast, 15 Apg proteins coordinate the formation of autophagosomes. Autophagy is a bulk degradation process induced by starvation in eukaryotic cells [1]. The Apg12 system is one of the ubiquitin-like protein conjugation systems conserved in eukaryotes. It was first discovered in yeast during systematic analyses of the apg mutants defective in autophagy. Covalent attachment of Apg12-Apg5 is essential for autophagy [2,3,4].

1: The pre-autophagosomal structure organized by concerted functions of APG genes is essential for autophagosome formation. Suzuki K, Kirisako T, Kamada Y, Mizushima N, Noda T, Ohsumi Y; EMBO J 2001;20:5971-5981. PMID:11689437

2: Formation of the approximately 350-kDa Apg12-Apg5.Apg16 multimeric complex, mediated by Apg16 oligomerization, is essential for autophagy in yeast. Kuma A, Mizushima N, Ishihara N, Ohsumi Y; J Biol Chem 2002;277:18619-18625. PMID:11897782

3: A new protein conjugation system in human. The counterpart of the yeast Apg12p conjugation system essential for autophagy. Mizushima N, Sugita H, Yoshimori T, Ohsumi Y; J Biol Chem 1998;273:33889-33892. PMID:9852036

4: Role of the Apg12 conjugation system in mammalian autophagy. Mizushima N, Yoshimori T, Ohsumi Y; Int J Biochem Cell Biol 2003;35:553-561. PMID:12672448