This domain is found at the C-terminal end of Transcriptional protein SWT1 from Saccharomyces cerevisiae and similar fungal proteins. SWT1 is an RNA endonuclease involved in quality control of nuclear messenger ribonucleoprotein particles (mRNPs). It consists of three domains: N-terminal, middle (Pfam:PF13638), and C-terminal domain (this entry). This domain shows three long antiparallel helices and three shorter helices. It shares characteristics with members of the HEPN domain (Pfam:PF05168) [1].

1: High-resolution crystal structure reveals a HEPN domain at the C-terminal region of S. cerevisiae RNA endonuclease Swt1. Peng S, Zhou K, Wang W, Gao Z, Dong Y, Liu Q; Biochem Biophys Res Commun. 2014;453:826-832. PMID:25450355