2012 Volume 24 Issue 136 Pages 65-77
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.
