This is the RRM fold domain prototyped by the version at the N-terminus of the TRADD protein. The TRADD-N domain is widely present in bacterial conflict systems and in a spectacular diversity of counter-invader systems in metazoa, especially in aggregating marine invertebrates. The domain is predicted to function as a signalling bridge linking invader sensing and effector deployment in multidomain proteins. Metazoans have two broad families of TRADD-N domains, the NCOA6 and the TRADD/DEDD-2 families respectively that are named after the prototypic vertebrate proteins in which they are found [1].

1: Bacterial death and TRADD-N domains help define novel apoptosis and immunity mechanisms shared by prokaryotes and metazoans. Kaur G, Iyer LM, Burroughs AM, Aravind L; Elife. 2021; [Epub ahead of print] PMID:34061031