Carbohydrate structural units in glycoproteins and polysaccharides as important ligands for Gal and GalNAc reactive lectins

Albert M. Wu*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

48 Scopus citations

Abstract

Glycoproteins (gps) contain many carbohydrate epitopes or crypto-glycotopes for Gal and GalNAc reactive lectins. They are present on the cell surface and function as receptors in various life processes. Many exist in soluble or gel form and serve as biological lubricants or as barriers against microbial invasion. During the past two decades, eleven mammalian structural units have been used to express the binding domain of applied lectins. They are: F, GalNAcα1→3GalNAc; A, GalNAcα1→3Gal; T, Galβ1→3GalNAc; I, Galβ1→3GlcNAc; II, Galβ1→ 4GlcNAc; B, Galα1→3Gal; E, Galα1→4Gal; L, Galβ1→4Glc;P, GalNAcβ1→3Gal; S, GalNAcβ1→4Gal and Tn, GalNAcα1→Ser(Thr). Except L and P, all of the units can be found in glycoproteins. Tn, which is an important marker for breast/colon cancer and vaccine development, exists only in O-glycans. Natural Tn gp, the simplest mammalian O-glycan, is exclusively expressed in the armadillo salivary gland. Antifreeze gp is composed of repeating units of T. Pneumococcus type XIV capsular polysaccharide has uniform II disaccharide as carbohydrate side chains. Asialo human α1-acid gp and asialo fetuin provide multi-antennary II structures. Human ovarian cyst gps, which belong to the complex type of glycoform, comprise most of the structural units. To facilitate the selection of lectins that could serve as structural probes, the carbohydrate binding properties of Gal/GalNAc reactive lectins have been classified according to their highest affinity for structural units and their binding profiles are expressed in decreasing order of reactivity. Hence, the binding relationship between glycoproteins and Gal/GalNAc specific lectins can be explored.

Original languageEnglish
Pages (from-to)676-688
Number of pages13
JournalJournal of Biomedical Science
Volume10
Issue number6 II
DOIs
StatePublished - 2003

Keywords

  • Applied lectins and carbohydrate specificities
  • Disaccharide units
  • Glycoproteins

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