This domain found in archaeal proteins, including PF2050 from Pyrococcus furiosus (Swiss:Q8TZE5). PF2050, with an overall globular structure, contain this domain twice, each showing an antiparallel beta-sheet and an alpha-helical bundle, and shows a positively charged basic cleft on one side. This protein interacts with circular and linear dsDNA [1].

1: Crystal structure of Pyrococcus furiosus PF2050, a member of the DUF2666 protein family. Han BG, Jeong KC, Cho JW, Jeong BC, Song HK, Lee JY, Shin DH, Lee S, Lee BI; FEBS Lett. 2012;586:1384-1388. PMID:22616997