The relationship between glycan structures and expression levels of an endoplasmic reticulum-resident glycoprotein, UDP-glucose: Glycoprotein glucosyltransferase 1.

Abstract In this article, we report a relationship between glycan structures and expression levels of a recombinant ER-resident glycoprotein, uridine 5′-diphosphate-glucose: glycoprotein glucosyltransferase (UGGT1). The function of glycan structures attached to a glycoprotein is actively studied; however, the glycan structures of recombinant, and not endogenous, glycoproteins have not been examined. In this study, we indicate a relationship between the glycan structure and the level of protein expression. Expression levels were controlled utilizing a series of vectors (pFN21K, pFN22K, pFN23K, and pFN24K HaloTag CMV Flexi Vectors). Qualitative and semi-quantitative confirmation of glycan structures was achieved with tandem mass spectrometry. The results of this study indicate that glycan structures are similar to endogenous glycans at low expression levels.