This is the RING domain of TNF receptor-associated factors 2/3/5 (TRAFs2/3/5). The RING domain is common among ubiquitin E3 ligases and it is found at the N-terminal of TRAFs, followed by a series of zinc fingers and a C-terminal MATH/TRAF domain. This domain, together with the zinc fingers, is required for ligase activity [1,2].

1: The activity of TRAF RING homo- and heterodimers is regulated by zinc finger 1. Middleton AJ, Budhidarmo R, Das A, Zhu J, Foglizzo M, Mace PD, Day CL; Nat Commun. 2017;8:1788. PMID:29176576

2: The Structure and Ubiquitin Binding Properties of TRAF RING Heterodimers. Das A, Middleton AJ, Padala P, Ledgerwood EC, Mace PD, Day CL; J Mol Biol. 2021;433:166844. PMID:33539883