Many proteins are glycosylated on certain residues, which can affect the proteome.
Glycans can interact with receptors, which in turn affect their cellular and subcellular localization. For example, cytokines and the subgroup chemokines are small signaling proteins that are involved in the immune response. Many of the N-linked glycans on these cytokines play an important role in metabolic turnover and by engineering the glycoform and its branching, there can be advantageous physiochemical affects on the immune response.
Furthermore, glycosylated proteins, or glycoproteins, can have increased resistance to degradation by proteases, which will increase the half-life of those proteins. For example, interferon beta  has been shown to be important in the treatment of multiple sclerosis. Recombinant versions of interferon beta have been produced in Escherichia coli, with the glycosylated form being more stable and resistant to protease degradation, while the non-glycosylated form is degraded much more quickly. Engineered glycoproteins have also been instrumental in enzyme replacement therapy (ERT). This has been of particular interest in the development of therapeutics for lysosomal storage disease. Proper delivery of these enzymes is highly dependent on the mannose 6-phosphate (M6P) tagging on N-glycans. Thus, engineering of these N-glyans, such as by modification of branching patterns, sialic acid capping, M6P tagging, monosaccharide constituents, and glycosidic bond linkage, there can be increased efficacy of lysosomal targeting and better delivery to the central nervous system through the blood brain barrier.
 Additionally, glycoengineering has been utilized with neural stem cell cultures to increase adhesion to the extracellular matrix through the treatment of an N-acetylmannosamine analog.