Complex carbohydrates, molecules that are particularly important for communication between cells, are under systematic study.
Carbohydrates are essential for life on Earth. In its simplest form, serving as the primary source of energy to sustain life. Mostly. However, there are no carbohydrates and simple sugars but as conjugates or molecular complex glycans, come in many shapes and sizes, to linear chains (polysaccharides) to highly branched molecules as ruffled antenna arms. And although the proteins and nucleic acids such as DNA have traditionally attracted much scientific attention, glycans are also key to life.
They are ubiquitous in nature, forming intricate sugar coat that surrounds the cells of virtually every niche and occupying the spaces between these cells. As part of the called extracellular matrix.
Glycans, with their diverse chemical structures play a key role in the transmission of important biochemical signals within and between cells. Thus, these sugars guide the cell communication who is essential for normal development of cells, tissues and physiological function of the body. For the most part, the polymers do not exist as glycans on the cell surface or in the extracellular matrix (ECM).
Rather, are assembled in specific proteins to form conjugates of proteoglycan or protein-glycans.
Complex sugars, or glycans, are a structurally diverse class of molecules that provide the molecular landscape critically cell surface and extracellular matrix (ECM) between cells. Typically these polysaccharides, represented here as colored beads chains, are covalently bonded to proteins (shown here in blue), many of which also reside on the cell surface and throughout the ECM. Glycans can be linear chains (GAG) or branched sugars. Also represented here are some of the intracellular components, such as the Golgi apparatus (where these glycans are produced) and lipid vesicles modified glucan exported proteins on the cell surface.
In recent years, we have studied a class of linear glycan known as glycosaminoglycans (GAGs, for short), in particular a subset known as HSGAGs, consisting of heparan sulfate and heparin. We are beginning to understand and appreciate the integral roles that these glycans play in numerous biological processes relevant to health and disease.