This archaeal domain of unknown function has been found at the middle of Methanogenesis regulatory protein FilR1 [1,2] and at the C-terminus of archaeal proteins, including several transcriptional regulators of the ArsR family (see Pfam:PF01022). FilR1 is a member of the two-component regulatory system FilI/FilRs which is involved in the regulation of methanogenesis.

1: Phyletic Distribution and Lineage-Specific Domain Architectures of Archaeal Two-Component Signal Transduction Systems. Galperin MY, Makarova KS, Wolf YI, Koonin EV; J Bacteriol. 2018; [Epub ahead of print] PMID:29263101

2: Characterization of an archaeal two-component system that regulates methanogenesis in Methanosaeta harundinacea. Li J, Zheng X, Guo X, Qi L, Dong X; PLoS One. 2014;9:e95502. PMID:24748383