Members of this family are thought to be integral membrane proteins. Some members of this family have been shown to cause apoptosis if mutated [1], these proteins are known as DAD for defender against death. The family also includes the epsilon subunit of the oligosaccharyltransferase that is involved in N-linked glycosylation [2].

1: Molecular cloning of a human cDNA encoding a novel protein, DAD1, whose defect causes apoptotic cell death in hamster BHK21 cells. Nakashima T, Sekiguchi T, Kuraoka A, Fukushima K, Shibata Y, Komiyama S, Nishimoto T; Mol Cell Biol 1993;13:6367-6374. PMID:8413235

2: The essential OST2 gene encodes the 16-kD subunit of the yeast oligosaccharyltransferase, a highly conserved protein expressed in diverse eukaryotic organisms. Silberstein S, Collins PG, Kelleher DJ, Gilmore R; J Cell Biol 1995;131:371-383. PMID:7593165