These proteins appear to be related to peptidases in peptidase clan CD that includes the caspases. This domain has been termed the CHAT domain for Caspase HetF Associated with Tprs. This family has been identified as a sister group to the separins [1].

1: Classification of the caspase-hemoglobinase fold: detection of new families and implications for the origin of the eukaryotic separins. Aravind L, Koonin EV; Proteins. 2002;46:355-367. PMID:11835511