Use of transmembrane FRET to investigate the internalization of glycosylated proteins

Abstract

The importance of glycans in various cellular events, especially intracellular and intercellular trafficking of proteins, has been reported in numerous studies. Here, we present a novel method to monitor endocytosis of proteins of interest bearing a specific glycan modification. Using a fl uorescence resonance energy transfer technique, we investigated the role of glycan structure on the internalization of insulin-responsive glucose transporter GLUT4. We found that sialylated glycoforms of GFP-tagged GLUT4 appear to be internalized more slowly than non-sialylated GLUT4 upon insulin removal. This novel glycan imaging tool allows probing functional roles of specific glycan modifications in endocytosis of various proteins.