This is a conserved, three transmembrane helix-containing domain found fused to certain prokaryotic YEATS domain. Genome context displacement patterns predict an effector role for this domain, as a membrane-perforating, cell-suicide response-enacting domain [1].

1: Identification of Uncharacterized Components of Prokaryotic Immune Systems and Their Diverse Eukaryotic Reformulations. Burroughs AM, Aravind L; J Bacteriol. 2020; [Epub ahead of print] PMID:32868406