This family of proteins represents the regulatory domain RD of RIG-I, a protein which initiates a signalling cascade that provides essential antiviral protection for the host. The RD domain binds viral RNA, activating the RIG-I ATPase by RNA-dependant dimerisation. The structure of RD contains a zinc-binding domain and is thought to confer ligand specificity [1].

1: The C-terminal regulatory domain is the RNA 5'-triphosphate sensor of RIG-I. Cui S, Eisenacher K, Kirchhofer A, Brzozka K, Lammens A, Lammens K, Fujita T, Conzelmann KK, Krug A, Hopfner KP; Mol Cell. 2008;29:169-179. PMID:18243112