Recently, the b-O-glycosidic attachment of 2-acetamido-2deoxy-D-glucose units to serine ((bGlcNAc)Ser) has been discovered (Figure 2). [19] The introduction of the b-O-GlcNAc moiety into nuclear pore proteins, transcription factors and cytoskeletal proteins seems to be involved in transcriptional regulation, analogous to the regulation of protein activity by phosphorylation. [20,21] Many glycoproteins that were isolated from yeast carry a-D-mannose units linked to serine ((aMan)Ser). [22] This includes recombinant human proteins such as the insulin-like Oliver Seitz, born in 1966, received his Diploma in chemistry from the University of Mainz in 1992 and obtained his Ph.D. degree there in 1995 under H. Kunz, developing a new linker for solid-phase glycopeptide synthesis. In 1996 he became a postdoctoral fellow working in the laboratories of C.-H. Wong at the Scripps Research Institute in La Jolla, California. He moved to the University of Karlsruhe in 1997 and started work towards his Habilitation under H. Waldmann. In 2000 he moved to Dortmund where he leads a group in the Department of Chemical Biology at the Max Planck Institute of Molecular Physiology and the Institute of Organic Chemistry at the University of Dortmund. His research interests include the synthesis and functionalisation of biopolymers such as peptides, glycopeptides, nucleic acids and analogues for further use as biomolecular tools in biological and medicinal research, and, most recently, the development of new strategies for the functionalisation of peptide nucleic acids.