Glycosylation is perhaps the most common and
versatile post-translational modification of proteins. It is
estimated that well over one-half of all mammalian proteins are
glycosylated. The roles of protein glycans, whether N- or O-linked
forms, are varied. Glycan is required for the biological function of
certain proteins, such as,
1. The Fc-effector function of immunoglobulin G (IgG).
2. The regulated clearance of the glycohormone lutropin (LH),
3. The targeting of lysosomal enzymes and,
4. Controlling the circulation lifetime of glycoprotein drugs (for
Glycans can also serve as:
- Recognition targets for their
complementary binding proteins, the lectins.
- Serving as sites of attachment by microbes
and toxins, and often constitute the first contact point between
pathogen and host.
- Protecting proteins from proteolytic
- Promoting protein foldinginto proper
tertiary and quaternary structure.
- Modulating the biological activities of