This is the C-terminal domain found in regnase-1, an RNase that directly cleaves mRNAs of inflammatory genes such as IL-6 and IL-12p40, and negatively regulates cellular inflammatory responses. The C-terminal domain is composed of three alpha helices and resembles ubiquitin associated protein 1 in structure [1].

1: Structural basis for the regulation of enzymatic activity of Regnase-1 by domain-domain interactions. Yokogawa M, Tsushima T, Noda NN, Kumeta H, Enokizono Y, Yamashita K, Standley DM, Takeuchi O, Akira S, Inagaki F; Sci Rep. 2016;6:22324. PMID:26927947