Glycomic approaches to study GlcNAcylation: Protein identification, site-mapping, and site-specific O-GlcNAc quantitation

Abstract

Background: O-Linked β-N-acetylglucosamine (O-GlcNAc) is an enzyme-catalyzed posttranslational modification of serine or threonine side chains of nuclear and cytoplasmic proteins. O-GlcNAc is present in all metazoans and in viruses that infect eukaryotic cells. GlcNAcylation is dynamic and has a high cycling rate on many proteins in response to cellular metabolism and various environmental stimuli. The rapid cycling of O-GlcNAc modulates many biological processes, including transcriptional regulation, stress responses, cell cycle regulation, and protein synthesis and turnover. Rationale: Despite the importance of O-GlcNAc, progress during the past two decades in this field has been slow. One of the major obstacles is the lack of simple and sensitive tools for efficient O-GlcNAc detection and localization. Recently developed O-GlcNAc derivatization and enrichment approaches, together with new techniques in mass spectrometric instrumentation and methods, have provided breakthroughs in O-GlcNAc site localization and site-specific quantitation. In this review, we will discuss how the current techniques are expanding our knowledge about O-GlcNAc proteomics/glycomics and functions. © 2008 Humana Press.