A conserved asparagine has a structural role in ubiquitin-conjugating enzymes.
Berndsen, C.E., Wiener, R., Yu, I.W., Ringel, A.E., Wolberger, C.(2013) Nat Chem Biol 9: 154-156
- PubMed: 23292652 
- DOI: https://doi.org/10.1038/nchembio.1159
- Primary Citation of Related Structures:  
4FH1 - PubMed Abstract: 
It is widely accepted that ubiquitin-conjugating enzymes contain an active site asparagine that serves as an oxyanion hole, thereby stabilizing a negatively charged transition state intermediate and promoting ubiquitin transfer. Using structural and biochemical approaches to study the role of the conserved asparagine to ubiquitin conjugation by Ubc13-Mms2, we conclude that the importance of this residue stems primarily from its structural role in stabilizing an active site loop.
Organizational Affiliation: 
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.