N-terminal RING finger (see <PDOC00449>)/B-box (see <PDOC50119>)/coiled coil (RBCC) or tripartite motif (TRIM) proteins, which are found in metazoan, are involved in a vast array of intracellular functions. They appear to function as part of large protein complexes and possess ubiquitin-protein isopeptide ligase activity. The following RBCC proteins contain an ~60-residue COS (C-terminal subgroup one signature) domain, which is also found in a distantly related non-RBCC microtubule-binding protein, GLFND:

• Vertebrate MID1 and MID2, which associate with microtubules through homo- and heterodimerization.
• Animal TRIM9, which plays a regulatory role in synaptic vesicle exocytosis.
• Mammalian TRIM nine-like (TNL).
• Mammalian TRIM36, which could play a regulatory role in exocytosis of the sperm vesicle.
• Mammalian tripartite, fibronectin type III and C-terminal B30.2/SPRY (TRIFIC).
• Mammalian muscle-specific RING finger (MURF) family. MURF proteins have an ability to form both homo- and heterodimers with each other and to associate with the microtubule cytoskeleton.

In addition to RBCC, the COS domain is also found in association with B30.2/SPRY (see <PDOC50188>) or fibronectin type-III (FN3) (see <PDOC50853>) domains.

The COS domain is predicted to consist of two α-helical coils [1].

The profile we developed covers the entire COS domain.