What is Glycobiology?
Defined in the broadest sense, glycobiology is the study of the structure, biosynthesis and biology of glycans that are widely distributed in nature. The central paradigm driving the modern revolution in molecular biology has been that biological information flows from DNA to RNA to protein. The power of this concept lies not only in its template-driven precision, but also in the ability to manipulate any one class of molecules based upon knowledge of another, and in the patterns of sequence homology and relatedness that predict function and reveal evolutionary relationships. With the completion of the genomic sequences of humans and several other commonly studied "model" organisms, one can anticipate even more spectacular gains in understanding biological systems. Given this success story, there is a tendency to assume that the study of DNA, RNA, and proteins will elucidate all of the important mechanisms of biology. In fact, creating cells and organisms requires two other major classes of molecules, lipids and sugars. These can serve as critical intermediates in generating energy, as signaling molecules, as structural components, or as determinants of cellular interactions. All cells and many proteins in nature are covered with a dense and complex array of covalently attached sugar chains (called oligosaccharides or glycans). The biological roles of these glycans become particularly important in constructing complex multicellular organs and organisms, a process which requires interactions of cells with one another, and with the surrounding extracellular matrix. Since most classes of glycans are on the outer surface of cellular and secreted macromolecules, they are in an optimal position to modulate or mediate a variety of events in cell-cell and cell-matrix interactions that are crucial to the development and function of a complex multicellular organism. They are also in a position to mediate interactions between organisms, e.g., between host and parasite. In addition, simple, rapidly turning-over protein-bound glycans are abundant in the nucleus and cytoplasm, where they appear to serve as regulatory switches. The chemistry, biochemistry and biology of sugars were matters of very prominent interest in the first half of the 20th century. However, during the initial phase of the modern revolution in molecular biology in the 1970s and 80s, studies of glycans lagged behind those of the other major classes of molecules. This was in large part due to the inherent structural complexity of glycans, the difficulty in easily determining their sequence, and the lack of in-depth information about the genetic control of their biosynthesis. The development of a variety of new technologies for exploring the structures of these chains and the cloning of most of the major genes involved in synthesizing them has now opened up a new frontier of molecular and cellular biology called glycobiology (a term coined in 1988 by Rademacher, Parekh, and Dwek). Since that time a very broad spectrum of functions have been revealed for glycans. Thus, glycobiology is also an integrative science, crossing all subfields of chemistry, biology, and medicine, in relation to all aspects of the structure, biosynthesis and function of glycans.