Sialyltransferases gangliosides

Figure 8. Location of gangliosides, sialidase, and sialyltransferase at the nerveending membrane...

Fig. 1.4.7. Early steps in combinatorial ganglioside biosynthesis [9]. The sites of (indirect) inhibition by 11 and 12 are indicated. Abbreviations Cer, ceramide, N-acylsphingosine Clc, glucose Gal, galactose GalNAc, N-acetylgalactosamine NeuAc, N-acetylneuraminic acid SAT, sialyltransferase GalNAcT, N-acetylgalactosaminyltransferase ...

Sialyltransferases transfer sialic acid moieties as the terminal residues in oligosaccharide side chains of animal cell coat proteins and gangliosides. In this assay, CMP-7V-acetylneuraminic acid was reacted with asialoglycoprotein to form cytidfne 5 -monophosphate (CMP) and the O-acetylneuraminic acid derivative of the protein. 

A bifunctional sialyltransferase Cst-II from C. jejuni OH4384 carrying both a2,3- and a2,8-sialyltransferase activities was used in the enzymatic synthesis of ganglioside mimic GD3 (66). 

More recently, studies on Campylobacter jejuni have demonstrated how specific bacterial carbohydrate antigens can mimic the fine structure of human cell surface glycolipid structures and elicit autoimmune reactivity. Yuki et al.61 first identified that the lipooligosaccharide (LOS) of C. jejuni mimicked human G(M)1 ganglioside and subsequently extended these studies to demonstrate that specific single amino acid variants of the C. jejuni Cst-II sialyltransferase protein are responsible for the synthesis of LOS variants that in turn, mimic different... 

Simmons, J. L., Fishman, P. H., Freese, E., Brady, R. O. (1975). Morphological alterations and ganglioside sialyltransferase activity induced by small fatty acids in HeLa cells. J. Cell Biol., 66, 414-424. 

Values are the mean of two experiments. Absolute values per g of brain were ganglioside NeuNAc, 1.4 /imol endogenous acceptor capacity (E A C), 245.616 cpm of n-NeuNAc incorporated into endogenous gangliosides after 60 min of incubation of membranes with CMP- H-NeuNAc CMP-NeuNAc lactosylceramide sialyltransferase activity (STA), 3,380,951 cpm of H-NeuNAc incorporated into lactosylceramide after 60 min of incubation with CMP-3H-NeuNAc. Relative concentration (RC) means ... 

---