This is the N-terminal ubiquitin-like domain, termed UblA, from autophagy protein ATG5 [1,2]. ATG5 comprises two ubiquitin-like domains (UblA and UblB) that flank a helix-rich domain (HBR). Both UblA and UblB comprise a five-stranded sheet and two-helices.

1: Structure of the human ATG12~ATG5 conjugate required for LC3 lipidation in autophagy. Otomo C, Metlagel Z, Takaesu G, Otomo T; Nat Struct Mol Biol. 2013;20:59-66. PMID:23202584

2: Structure of Atg5.Atg16, a complex essential for autophagy. Matsushita M, Suzuki NN, Obara K, Fujioka Y, Ohsumi Y, Inagaki F; J Biol Chem. 2007;282:6763-6772. PMID:17192262