Arabinoxylan (AX) is the major hemicellulose in grass cell walls as a component of lignocellulosic biomass with the highest abundance and yield on terrestrial land area. AX is an obstacle for biomass saccharification as the structural polysaccharides linked to lignin from the supporting tissues like culm and sheath of the grass energy crops, while it has immunomodulatory and prebiotic functions as the dietary fibers from cereal grains. AX is thus interesting from two points of view: the use of a carbon-neutral and renewable energy resource and the use of a healthy functional polysaccharide like barley β-glucan. Elucidation of its fine structures and biosynthetic mechanisms contributes the field evaluation of energy crops and cereal cultivars, as well as for functional food developments. This review outlines the current research status of the chemical structure and biosynthetic mechanism of AX, together with the development of its use as a health-functional polysaccharide.

Galectins are carbohydrate-binding proteins that do not require metals, and are widely distributed in vertebrates. The basic specificity of galectins for β-galactosides is conserved in their carbohydrate recognition domains (CRDs). Although galectins have been implicated in important biological functions, there is limited evidence that galectin-galactoside binding is directly linked to such functions. Extensive functional analysis of galectins in a large number of species is necessary to understand the broad range of evolutionarily conserved functions. Therefore, we focused on Xenopus galectins and identified and analyzed 12 species of Xenopus laevis galectins. The only non-mammalian vertebrate that has been comprehensively analyzed for galectins is the Xenopus laevis, which we use as a model for galectin research. In this review, we introduce the types of galectins and the functions of Xenopus galectins available to date.

In the intestine, mucins function as a physical barrier separating the gut bacteria and the host. MUC2 mucin is a highly O-glycosylated glycoprotein, and its glycans are an essential post-translational modification for MUC2 function. In recent years, it has been discovered that specific structural units of the complex MUC2 glycans play distinct physiological functions. In particular, the sulfation of GlcNAc and Galactose in MUC2 glycans is essential for intestinal barrier function. Furthermore, gut bacteria utilize mucin sugar chains as a nutrient source by employing specific sulfatase enzymes, allowing them to colonize in the intestine. On the other hand, gut bacteria regulate host glycosylation through the induction of glycosyltransferase expression. In the light of recent studies on the structure and function of MUC2 glycans, mucins are not only functioning as a physical barrier but also as molecules that mediate complex interactions with gut microbiota. In this article, we discuss the function of MUC2 mucin and its glycosylation, with a particular focus on sulfated glycans.

Glycosaminoglycans (GAGs) on the cell surface and in the extra cellular matrix have multiple biological roles, including cell signaling. They have a characteristic repeating disaccharide structure and are sulfated by sulfotransferases, the resulting combination of which governs which signal ligands bind to them.

Mouse and human pluripotent stem cells have the potential to differentiate into all cell types, and many signalings and growth factors regulate their states of pluripotency and differentiation. Recent studies are elucidating the specific roles of GAGs in controlling pluripotency and differentiation of pluripotent stem cells through signaling regulation. In this minireview, we present the functions of GAGs in pluripotent stem cells that have been elucidated so far.

Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are a group of proteins anchored to glycolipid on the cell membrane and are ubiquitous in eukaryotes. The basic structure of the glycosylphosphatidylinositol (GPI) moiety comprises ethanolamine phosphate, three mannose residues, glucosamine and phosphatidylinositol (PI). This basic structure and the mechanism by which proteins are anchored to membranes via the structure are conserved among organisms. After the identification of paroxysmal nocturnal hemoglobinuria (PNH), diseases derived from GPI anchor deficiencies were discovered. To comprehend these diseases fully, a comprehensive understanding of GPI anchor biosynthesis, encompassing the intricate remodeling of glycans and lipids, becomes imperative. We used mutant strains of Saccharomyces cerevisiae in which the gene encoding the enzyme that catalyzes remodeling was knocked out and a model molecule for GPI-APs to observe the remodeling process. Herein, we introduce a method for analyzing and identifying glycan structures in GPI anchors using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI MS).

Arabinoxylan (AX) is the major hemicellulose in grass cell walls as a component of lignocellulosic biomass with the highest abundance and yield on terrestrial land area. AX is an obstacle for biomass saccharification as the structural polysaccharides linked to lignin from the supporting tissues like culm and sheath of the grass energy crops, while it has immunomodulatory and prebiotic functions as the dietary fibers from cereal grains. AX is thus interesting from two points of view: the use of a carbon-neutral and renewable energy resource and the use of a healthy functional polysaccharide like barley β-glucan. Elucidation of its fine structures and biosynthetic mechanisms contributes the field evaluation of energy crops and cereal cultivars, as well as for functional food developments. This review outlines the current research status of the chemical structure and biosynthetic mechanism of AX, together with the development of its use as a health-functional polysaccharide.

Galectins are carbohydrate-binding proteins that do not require metals, and are widely distributed in vertebrates. The basic specificity of galectins for β-galactosides is conserved in their carbohydrate recognition domains (CRDs). Although galectins have been implicated in important biological functions, there is limited evidence that galectin-galactoside binding is directly linked to such functions. Extensive functional analysis of galectins in a large number of species is necessary to understand the broad range of evolutionarily conserved functions. Therefore, we focused on Xenopus galectins and identified and analyzed 12 species of Xenopus laevis galectins. The only non-mammalian vertebrate that has been comprehensively analyzed for galectins is the Xenopus laevis, which we use as a model for galectin research. In this review, we introduce the types of galectins and the functions of Xenopus galectins available to date.

In the intestine, mucins function as a physical barrier separating the gut bacteria and the host. MUC2 mucin is a highly O-glycosylated glycoprotein, and its glycans are an essential post-translational modification for MUC2 function. In recent years, it has been discovered that specific structural units of the complex MUC2 glycans play distinct physiological functions. In particular, the sulfation of GlcNAc and Galactose in MUC2 glycans is essential for intestinal barrier function. Furthermore, gut bacteria utilize mucin sugar chains as a nutrient source by employing specific sulfatase enzymes, allowing them to colonize in the intestine. On the other hand, gut bacteria regulate host glycosylation through the induction of glycosyltransferase expression. In the light of recent studies on the structure and function of MUC2 glycans, mucins are not only functioning as a physical barrier but also as molecules that mediate complex interactions with gut microbiota. In this article, we discuss the function of MUC2 mucin and its glycosylation, with a particular focus on sulfated glycans.

Glycosaminoglycans (GAGs) on the cell surface and in the extra cellular matrix have multiple biological roles, including cell signaling. They have a characteristic repeating disaccharide structure and are sulfated by sulfotransferases, the resulting combination of which governs which signal ligands bind to them.

Mouse and human pluripotent stem cells have the potential to differentiate into all cell types, and many signalings and growth factors regulate their states of pluripotency and differentiation. Recent studies are elucidating the specific roles of GAGs in controlling pluripotency and differentiation of pluripotent stem cells through signaling regulation. In this minireview, we present the functions of GAGs in pluripotent stem cells that have been elucidated so far.

Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are a group of proteins anchored to glycolipid on the cell membrane and are ubiquitous in eukaryotes. The basic structure of the glycosylphosphatidylinositol (GPI) moiety comprises ethanolamine phosphate, three mannose residues, glucosamine and phosphatidylinositol (PI). This basic structure and the mechanism by which proteins are anchored to membranes via the structure are conserved among organisms. After the identification of paroxysmal nocturnal hemoglobinuria (PNH), diseases derived from GPI anchor deficiencies were discovered. To comprehend these diseases fully, a comprehensive understanding of GPI anchor biosynthesis, encompassing the intricate remodeling of glycans and lipids, becomes imperative. We used mutant strains of Saccharomyces cerevisiae in which the gene encoding the enzyme that catalyzes remodeling was knocked out and a model molecule for GPI-APs to observe the remodeling process. Herein, we introduce a method for analyzing and identifying glycan structures in GPI anchors using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI MS).