N-glycan metabolism and plant cell differentiation and growth


4 被引用数 (Scopus)


Free N-glycans are present at micromolar concentrations in plant cells during their differentiation, growth and maturation stages, and might play a role in processes such as seed germination and fruit ripening. The structure of free N-glycans, which are found in hypocotyls and developing seeds and fruit, can be classified into two types: a high-mannose type (HMT) and a plant complex type (CT); the former, in most cases, has only one GlcNAc residue, while the latter has a chitobiose unit. It is thought that the enzyme endo-β-N- acetylglucosaminidase (endo-β-GlcNAc-ase) is involved in the production of HMT sugar chains, whereas the enzyme peptide:N-glycanase (PNGase) is involved in the production of plant CT sugar chains. However, the mechanism and significance of free N-glycan production in plant cells remain obscure. To characterize N-glycan metabolism and the physiological function of free sugar chains, we have investigated the substrate specificities, intracellular distributions, and gene structures of endo-β-GlcNAc-ase, PNGase, and α-mannosidase in various plants. Here, we report our discovery that endo-β-GlcNAc-ase activity begins to increase at a specific stage of tomato ripening, and that the amount of free N-glycans dramatically increases in conjunction with this event. In addition, the structural properties of free N-glycans also change notably as the fruit ripens. This review describes N-glycan metabolism in plant cells, and proposes a role for free sugar chains in the differentiation and growth of plants. The recent finding that plant CT sugar chains are immunoactive is also discussed.

ジャーナルTrends in Glycoscience and Glycotechnology
出版ステータスPublished - 9月 2005

ASJC Scopus subject areas

  • 生化学
  • 有機化学


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