| Symbol: | UBX |
| UBX | |
| Pfam: | PF00789 |
| Pfam Clan: | CL0072 |
| Interpro: | IPR001012 |
| Smart: | UBX |
| Scop: | 1i42 |
In molecular biology, the UBX protein domain is found in ubiquitin-regulatory proteins, which are members of the ubiquitination pathway, as well as a number of other ubiquitin-like proteins including FAF-1 (FAS-associated factor 1), the human Rep-8 reproduction protein and several hypothetical proteins from yeast. The function of the UBX domain is not known although the fragment of avian FAF-1 containing the UBX domain causes apoptosis of transfected cells.
So far, as yet, no general function for the UBX domain has yet emerged.[1] Additionally, the absence of a carboxy-terminal di-glycine motif, however, indicates that UBX domains are not covalentlyattached to target proteins in a ubiquitin-like manner.[2]
The UBX domain comprises about 80 amino acid residues. They are distinct structural unitsdefining a large family of proteins that often exhibit a modular domain architecturethree-dimensional structures of UBX domains reveal a close structural relationship with ubiquitin despite the lack of significant sequence homology[2]
UBX domain is very similar to ubiquitin which gives us some indication of evolution. There are ubiquitin fusion which seem to be advantageous for ribosomal subunit folding.[2]