Structural domains comprising this superfamily share the structure of the yeast autophagy-related protein 6 (Atg6), also designated vacuolar protein sorting-associated protein 30 (Vps30), and its human homologue Beclin 1. These proteins where initially identified to play an key role in vacuolar protein sorting. In Saccharomyces cerevisiae, ATG6 and ATG14 form a protein complex required for autophagy, known as the yeast complex I with class III phosphatidylinositol 3-kinase (PI3KC3) activity. In mammals, Beclin 1 appears to be an obligate component of two distinct PI3K complexes, one involving the human ortholog of ATG14/Barkor, which corresponds to yeast complex I, and the other involving UVRAG. The ATG14/Barkor-containing PI3K complex is believed to be responsible for autophagic vesicle nucleation whilst the UVRAG-containing complex functions in the vacuolar protein sorting pathway PMID:22310240. Beclin 1 both promotes autophagy and inhibit tumorigenesis, as it coordinately regulates the autophagy and membrane trafficking involved in several physiological and pathological processes PMID:21311563,PMID:22170155.