FAQ: What are the differences between mammalian, yeast, insect (baculovirus), and plant cell expression systems?

Expression of glycoproteins in mammalian cells will result in mammalian-type glycosylation. For human proteins this is ideal, however some cell lines will add the non-human Gal α1-3 Gal epitope and the N-glycolylneuraminic acid (NGNA). Insect expression systems will add shorter N-glycans, with little sialylation. Plant cells typically have glycans that contain extra fucose and xylose residues. Yeast expression systems have a very different glycosylation pattern from mammalian cells, with only mannose-containing glycans.

Determining the optimal expression system depends on the target protein and/or the experimental needs. Early steps in glycoprotein synthesis (in the ER) are very similar across eukaryotes. Folding and ER glycosylation are intimately connected processes, so any eukaryotic system could potentially yield a properly folded protein. For more information see Biosynthesis of Glycans in Eukaryote