Branched oligosaccharides

Imata, H., Kubota, K., Hattori, K., et al. (1997) The specificity of association between concanavalin A and oligosaccharide-branched cyclodextrins with an optical biosensor. Bioorg. Med. Chem. Lett. 7 109-112. 

Fig. 3.4 The glycosylation pathway via ER and Golgi apparatus, in the cytosol carbohydrates are attached to a lipid precursor, which is then transported into the lumen of the ER to finish core glycosylation. This glycan is now attached to the nascent, folding polypeptide chain (which is synthesized by ribosomes attached to the cytosolic side of the ER from where it translocates into the lumen) and subsequently trimmed and processed before it is folded and moved to the Golgi apparatus. Capping of the oligosaccharide branches with sialic acid and fucose is the final step on the way to a mature glycoprotein [23].

Bierhuizen, M.F.A., and Fukuda, M., 1993, 3-l,6-N-acetylglucosaminyl transferases Enzymes critically involved in oligosaccharide branching. Trends in Glycoscience and Glycotechnology 6 17-28. 

Terms designating branches should be enclosed in square brackets. In a branched chain, the longest chain is regarded as the parent. If two chains are of equal length the one with lower Iocants at the branch point is preferred, although some oligosaccharides are traditionally depicted otherwise, such as the blood group A trisaccharide exemplified below. 

Figure 52-6. Diagrammatic representation of the structures of the H, A,and B blood group substances. R represents a long complex oligosaccharide chain, joined either to ceramide where the substances are glycosphingolipids, or to the polypeptide backbone of a protein via a serine or threonine residue where the substances are glycoproteins. Note that the blood group substances are biantenna ry ie, they have two arms, formed at a branch point (not indicated) between the GIcNAc—R, and only one arm of the branch is shown. Thus, the H, A,and B substances each contain two of their respective short oligosaccharide chains shown above. The AB substance contains one type A chain and one type B chain.

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