This domain is found in pore-forming toxin stonustoxin (SNTX), a lethal venom found in Synanceia horrida. Because of the thioredoxin-like nature of the domain, it is referred to as the THX domain. The THX domain is comprised of a five-stranded beta-sheet and shares greatest structural similarity with Saccharomyces cerevisiae mitochondrial THX3. It is thought that THX domain plays a purely structural role [1].

1: Stonefish toxin defines an ancient branch of the perforin-like superfamily. Ellisdon AM, Reboul CF, Panjikar S, Huynh K, Oellig CA, Winter KL, Dunstone MA, Hodgson WC, Seymour J, Dearden PK, Tweten RK, Whisstock JC, McGowan S; Proc Natl Acad Sci U S A. 2015;112:15360-15365. PMID:26627714