* UGGT is a large soluble protein (150-170 kDa) that is mostly ER retained.
* This is the glycoprotein folding sensor enzyme. If the glycoprotein is incompletely folded, the misfolded protein is recognized in the context of its N-glycan by the folding sensor UGGT. UGGT puts back one α(1-3)Glc, and refolding is again attempted by CNX/CRT.
* Proteins unable to properly fold after multiple cycles are eventually retro-translocated to the cytosol to be degraded by the proteasome, a process known as endoplasmic reticulum-associated degradation (ERAD).
* It is currently thought that the N-terminal may bind the misfolded polypeptide, while the C-terminal performs glycosyltransferase activity. In humans there are two proteins mediating this enzyme activity.
* Although extensively distributed in nature, UGGT is not required for single cell viability under normal conditions.