Research in the Moremen lab focuses on the structure, regulation, and localization of enzymes involved in the biosynthesis, recognition, and catabolism of mammalian glycoproteins. Carbohydrate structures on glycoproteins contribute to many biological recognition events during development, oncogenic transformation, and cell adhesion. In addition, protein-linked glycans can influence bioactivity, folding, localization, and immunogenicity of the attached polypeptide. Large numbers of intracellular and extracellular proteins contain covalently bound oligosaccharides, including enzymes, cell-surface receptors, hormones, immunoglobulins, and viral antigens. Alterations in the synthesis and degradation of these structures can also occur in human genetic diseases and cancer. Despite the ubiquity of glycoprotein structures, much is still unknown about the regulation of the glycosylation pathway and aspects of structure and function of the processing enzymes. Many questions also remain regarding oligosaccharide catabolism in different intracellular compartments as well as the specificity and regulation of protein-carbohydrate interactions during development.