Glycans – the third revolution in evolution
Autoimmunity: Altered self-N-glycans trigger innate-mediated autoimmunity
Steven J Van Dyken and Richard M Locksley
According to the one origin of life theory, called glyco-world, carbohydrates are thought to be the original molecules of life, which provided molecular basis for the evolution of all living things.
The most abundant monosaccharides that can be found in animal glycan are: fucose (Fuc), galactose (Gal), glucose (Glu), mannose (Man),-acetylgalactosamine (GalNAc),=-acetylglucosamine (GlcNAc), sialic acid (Sia) and xylose (Xyl).
Glycans enable adaptive response to environmental changes and, unlike other epiproteomic modifications, which act as off/on switches, glycosylation significantly contributes to protein structure and enables novel functions. The importance of glycosylation is evident from the fact that nearly all proteins invented after the appearance of multicellular life are composed of both polypeptide and glycan parts.