The basic six-helix structure of the domain appears to be conserved as far back as the ced-3 and ced-4 genes in C. elegans, the organism in which several components of the apoptotic machinery were first characterized.
Osnovna šestoheliksna struktura domena je konzervirana od sisara sve do ced-3 i ced-4 gena kod C. elegans, organizma kod kojeg je nekoliko komponenti apoptozne mašinerije prvo okarakterisano.