Work in the Moremen lab is focused on four main areas: (1) characterization of mammalian glycoprotein biosynthesis and catabolism by the cloning, large-scale expression, biochemical characterization, and structure determination of the mammalian enzymes involved in these processes, (2) determination of the structural and molecular basis for the enzyme-substrate interactions for glycosidases and glycosyltransferases including mechanistic studies and identification of selective inhibitors, (3) developing technologies for detailed transcript profiling for glycan-related genes and correlating glycosylation enzyme expression with cellular glycan structures and (4) characterization of endoplasmic reticulum (ER) and Golgi enzymes involved in glycan biosynthesis and quality control degradation of misfolded nascent glycoproteins in the ER.