We are helped in our deliberations by the fact that, in biopharmaceutical manufacturing, the majority of cell lines with the capacity to glycosylate (which may be derived from either the animal, plant or fungal kingdoms) produce their differing glycan profiles through the way they combine the same basic monosaccharides. Thus, mammalian species use fucose, mannose, galactose, N-acetylglucosamine, N-acetylgalactosamine and sialic acid (of one form or another) in various combinations for their N- and O-glycans (for a more detailed discussion of glycan structures see here). These monosaccharides are found to one degree or another on all mammalian cell lines. As we move down through the evolutionary tree (or across taxonomic classification, depending on your point of view) we find that the number of different types of monosaccharides used in glycans decreases. Thus, insects do not have sialic acid in their glycans and neither do plants.
Fungal species can exhibit variation in the monosaccharides they use depending on the species being considered. For example, Saccharomyces sp. use only mannose and N-acetylglucosamine in their glycans but Aspergillus sp. can use these same monosaccharides plus galactose, thus the range of monosaccharides used is simpler still. Mammalian species therefore have the most developed glycan processing pathway in terms of the types of monosaccharide used. One caveat to this is that plants can also use xylose in their N-glycans, a monosaccharide that is not seen in the N- or O-glycans of animals.
The structures of commonly encountered monosaccharides used by various organisms are shown in Figure 1 below.