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.
| UBX | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 solution structure of the ubx domain of kiaa0794 protein | |||||||||
| Identifiers | |||||||||
| Symbol | UBX | ||||||||
| Pfam | PF00789 | ||||||||
| Pfam clan | CL0072 | ||||||||
| InterPro | IPR001012 | ||||||||
| SMART | UBX | ||||||||
| SCOP2 | 1i42 / SCOPe / SUPFAM | ||||||||
| |||||||||
Function
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]
Structure
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]
Homology
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]