Atg101 is a critical autophagy factor that functions together with ULK, Atg13 and FIP200 [1, 2]. Atg101 has been shown to be a HORMA (Hop1, Rev7 and MAD2) domain protein with an open conformation [3].

1: Atg101, a novel mammalian autophagy protein interacting with Atg13. Hosokawa N, Sasaki T, Iemura S, Natsume T, Hara T, Mizushima N; Autophagy. 2009;5:973-979. PMID:19597335

2: A novel, human Atg13 binding protein, Atg101, interacts with ULK1 and is essential for macroautophagy. Mercer CA, Kaliappan A, Dennis PB; Autophagy. 2009;5:649-662. PMID:19287211

3: Open and closed HORMAs regulate autophagy initiation. Suzuki H, Kaizuka T, Mizushima N, Noda NN; Autophagy. 2015;11:2123-2124. PMID:26389686