The tripartite motif-containing protein (Trim) family is defined by the presence of a common domain structure composed of a RING finger, a B-box, and a coiled-coil motif []. Trim36 is a E3 ubiquitin-protein ligase that mediates ubiquitination and subsequent proteasomal degradation of target proteins. It interacts with centromere protein-H, one of the kinetochore proteins and is involved in chromosome segregation and cell cycle regulation [, ]. It may play a role in the acrosome reaction and fertilisation [, ].
This domain, consisting of the distinct N-terminal PRY subdomain followed by the SPRY subdomain, is found at the C terminus of TRIM36. TRIM36 (also known as Haprin or RNF98) has a ubiquitin ligase activity and interacts with centromere protein-H, one of the kinetochore proteins. It has been shown that TRIM36 is potentially associated with chromosome segregation and that an excess of TRIM36 may cause chromosomal instability []. In Xenopus laevis, TRIM36 is expressed during early embryogenesis and plays an important role in the arrangement of somites during their formation [].
This entry represents the COS domain found in the C-I subfamily of the tripartite motif (TRIM) family of E3 ubiquitin ligases.The C-1 subfamily includes MID1 (TRIM18), MID2 (TRIM1), TRIM9, TNL (TRIM67), TRIM36 and TRIFIC (TRIM46) [, , ]. The C-I subfamily contains C-terminal FNIII and B30.2 domains which are associated with microtubules [, ]. C-I subfamily members also contain a relatively conserved region of approximately 60 amino acids, termed the C-terminal subgroup One Signature (COS) domain []. The human Midline-1 (MID1) COS domain has a helix-loop-helix structure in which the N- and C-terminal ends are in close proximity []. Deletion of the human MID1 COS domain does not affect MID1 dimerisation but disrupts localisation to the microtubules [].The COS domain is also observed within the TRIM C-II subgroup, which consists of the MURF1-3 proteins that do not contain the FNIII and B30.2domains. MUF1-3 proteins are also associated with microtubules [].
