(A) Schematic representation of the domain composition of TRIM family proteins. (B) Canonical structure of a core RING domain (PDB: 5FER) with secondary structural elements and Zn²⁺-binding sites indicated. (C) Schematic depicting the multiple conformational states of E2∼Ub conjugates: the ‘open conformation’ and the ‘closed conformation’ formed upon interaction with RING domains in which ubiquitin contacts the E2 and the thioester bond is primed for ubiquitin transfer.