TRIM33 is a member of the tripartite motif (TRIM) family of proteins, which are characterized by an N-terminal tripartite motif typically containing one RING-finger domain, one or two zinc-finger domains (B1 box and B2 box), and an associated coiled-coil region. Most TRIM proteins possess E3 ligase activity and are involved in the ubiquitin-dependent degradation of a number of important proteins. Four of the TRIM family proteins, TRIM24 (TIF1α), TRIM28 (TIF1β), TRIM33 (TIF1γ) and TRIM66, possess C-terminal plant homeodomain (PHD) and bromodomain (BRD) modules (Figure and), which bind to methylated lysine (KMe n ) and acetylated lysine (KAc), respectively.