The authors developed a method of synthesis of oligosaccharides using cell function. By administering the saccharide primer that is amphiphilic alkylglycoside into cell culture medium, glycosylated products were collected from the medium after 1-2 days. The sequences of the products were dependent on the biosynthetic pathway of sugars in the cells. By combining the saccharide primer and cell lines, it was possible to synthesize many kinds of oligosaccharides. The introduction of a functional group in an alkyl chain of saccharide primer made it possible to polymerize and immobilize to solid support. The saccharide primer method is expected to become a new methodology for glycomics.
Lipid rafts, glycosphingolipid and cholesterol-rich microdomains of plasma membrane, are implicated in signal transduction because a variety of signaling molecules, such as heterotrimeric G proteins and G protein-coupled receptors, are associated with them. Dynamic assemblies of lipid rafts with these molecules by extracellular events conduct signaling and sequentially regulate certain physical responses. This review focuses on the role of lipid rafts as a spatial compartment enriched in components of heterotrimeric G protein signaling.
Almost every organism contains a broad range of carbohydrate chains linked to many biomolecules. The complex carbohydrate chains of glycoproteins (O-glycans and N-glycans), glycolipids, and proteoglycans represent the secondary gene products formed through the reactions of many glycosyltransferases. The carbohydrate antigens on cell surface are regulated by many glycosyltransferases. Bioinformatics is a very powerful tool in the field of glycoproteomics as well as of genomics and proteomics. Bioinformatics technique accelerates the comprehensive identification and in silico cloning of glycosyltransferases. Glycosyltransferase genes play central roles in carbohydrate chain biosynthesis and have been analyzed for their biological functions. At present, over 173 genes of human glycosyltransferases and sulfotransferases have been identified, cloned and expressed in various expression systems to analyze the activity for carbohydrate synthesis and its biological function. The recombinant proteins of glycosyltransferases were successfully identified for their enzyme activities and substrate specificities. This article reviews the functions, substrate specificities and enzymatic reactions of glycosyltransferases such as β1,3-glycosyltransferase family which is cloned by bioinformatics techniques etc..
To uncover novel glycosyltransferase (GT) genes from the entire human genome, we have developed a computational method for determining the transmembrane region of Golgi-localized signal-anchor-type GT. The characteristics of GT were extracted by comparison with those of the plasma-membrane-localized signal-anchor-type membrane protein (PM) and the protein with signal peptide (SP), whose topologies are similar to that of GT. The Golgi-membrane-spanning region of GT was distinguished from PMs and SPs with sensitivity and specificity exceeding 95% using the position-specific score matrix (PSSM) of amino acid propensity based on hydropathy alignment. Using our algorithm for determining the Golgi-membrane-spanning region of GTs, an improvement in the efficiency of GT gene detection is expected.