LETTER TO THE EDITOR Structural insights into the TRIM family of ubiquitin

TRIM proteins play important roles in a wide range of biological processes, including cell proliferation, dif-ferentiation, development, apoptosis, oncogenesis and innate immunity [1, 2]. The N-terminal regions of all TRIM proteins contain a RING finger domain followed by one or two B-box domains and a coiled-coil domain (CCD). The RING-finger domain comprises conserved cysteine and histidine residues that bind two zinc at-oms in a ‘cross-brace ’ arrangement, and is essential for recruiting the ubiquitin-charged ubiquitin-conjugating enzymes (E2~Ub). The B-box domains, differing in both the number and spacing of the conserved cysteine and histidine residues [3], are typically composed of B1 and B2 domains, but some TRIM members only contain a B2 domain. CCD following the B-box domains has bee