What are the main differences between the recombinant proteins produced by different expression systems?

The main difference between the recombinant proteins produced by different expression systems is the post-translational modification carried by these proteins, such as glycosylation modification. The recombinant protein produced in Escherichia coli was not glycosylated. The recombinant protein produced in insect cells usually has partial glycosylation, but does not contain galactose and sialic acid, and the sugar chain has no complex branches. The recombinant protein produced in mammalian cells will carry complete glycosylation modification.