Cover Picture: Effect of Ganglioside GM3 Synthase Gene Knockout on the Glycoprotein N ‐Glycan Profile of Mouse Embryonic Fibroblast (ChemBioChem 1/2013)

The cover picture shows that gene knockout of the enzymes responsible for glycosphingolipid (GSL) synthesis significantly influences the biosynthesis of glycoprotein N ‐glycans. On p. 73 ff., S.‐I. Nishimura et al. describe how they have established a general and comprehensive glycomics protocol of cellular GLSs and N ‐glycans of glycoproteins. To test the feasibility of a glycoblotting‐based protocol, whole glycans released both from GLSs and glycoproteins were profiled concurrently by using the GM3 synthase‐deficient mouse embryonic fibroblast GM3(−/−). GM3(−/−) cells did not synthesize GM3 or any downstream product of GM3 synthase. Instead, expression levels of o‐series gangliosides involving GM1b and GD1‐α were increased dramatically whereas a‐/b‐series gangliosides were predominantly detected in wild‐type cells. It was also discovered that glycoprotein N‐glycan profiles of GM3(−/−) cells are significantly different from those of WT cells, though GM3 synthase is responsible only for GSL synthesis and is not associated with glycoprotein N ‐glycan biosynthesis.