The authors have developed the new positron emitting metal and fluorescence labeling protocol of ε-amino group of lysine through their rapid 6π-azaelectrocyclization. Using the same reaction, the small organic molecules could also be introduced on the amino groups of the living cell surface with simple operations under quite mild conditions, establishing the chemistry-based cell surface engineering with complex-type N-glycans. PET and the noninvasive fluorescence imaging of the N-glycoproteins and the world’s largest N-glycoclusters, mimicking the natural glyco-bioenvironment, for the first time visualized the differences in their in vivo dynamics and excretion pathway depending on the presence of the non-reducing end sialic acid as well as their linkages to the galactose residue. The authors also synthetically developed the artificial lymphocytes to target the tumors in living animals by introducing the complex-type N-glycans on the cell surfaces.
In eukaryotic glycoproteins, the N-glycan plays an important role with respect to both their structure and function. On the rough endoplasmic reticulum (rER) membrane, the N-glycan precursor is biosynthesized as a dolichol-linked oligosaccharide (DLO), which consists of fourteen sugars linked to pyrophosphoryl- dolichol. For completion of full-length DLO (Glc3Man9GlcNAc2-PP-dolichol), activities of at least eleven glycosyltransferases localized on the rER membrane are essential. Although twelve human genes for these enzymes have been identified, any physical interactions among them have not yet been systematically analyzed. In this review, we describe several physical interactions among them that were uncovered using the yeast split-ubiquitin system. Moreover, on the basis of observations obtained by this technique, novel models for networking among human glycosyltransferases can be proposed.
Effective tests for detecting a virus are important because of the increased risk of exposure to newly emerging and highly infectious pathogens due to global warming and increasing international travel. Time-consuming and highly sensitive methods for detection enable a pathogen to be detected during the early phase of infection; however, simple and quick detection testing that can be performed anywhere is often required, particularly in the case of high infectability and mortal diseases. In this review, we introduce a synthetic approach and optical property of a novel lectin detection utilizing carbohydrate–protein-specific recognition and aggregation-induced emission effect though a few examples and also discuss the emission mechanism.