Glycan

A glycan, also known as a polysaccharide or carbohydrate polymer, is a complex carbohydrate molecule formed by the repeated joining of monosaccharides (simple sugars) via glycosidic bonds. Glycans are ubiquitous in biology and play crucial roles in various cellular processes, including cell recognition, signaling, structural support, and energy storage. They can vary significantly in size, composition (type and ratio of monosaccharides), branching, and linkage patterns, leading to diverse biological functions. Glycans are essential components of glycoproteins, glycolipids, and proteoglycans. They are classified based on their monomer composition and linkage patterns and are extensively studied in glycobiology.

Glycan meaning with examples

• Glycans are essential components of the cell surface, where they participate in cell-cell interactions. These complex sugar structures often act as recognition signals, mediating processes such as immune cell activation and pathogen binding. Different cell types express unique glycan profiles, allowing for precise communication. The study of cell-surface glycans is vital for understanding diseases like cancer.
• The bacterial cell wall is largely composed of glycans, such as peptidoglycan. This rigid layer provides structural support and protects the bacterium from environmental stresses. The composition of bacterial glycans differs significantly from those of host organisms, making them ideal targets for antimicrobial drugs. Targeting the synthesis or structure of bacterial glycans helps combat infections.
• Glycans are also found as important components in the extracellular matrix (ECM), which is a network of proteins and polysaccharides that provides structural support and organizes tissues. The ECM's glycan composition can be altered in diseases, and the glycan chains on matrix molecules can bind and sequester growth factors.
• During protein glycosylation, glycans are covalently attached to proteins, forming glycoproteins. This process often affects protein folding, stability, and function. Aberrant glycosylation patterns are often found in cancer cells and can be used as diagnostic or prognostic biomarkers. Analysis of protein-bound glycans is essential.
• Glycans also serve as an important source of energy storage in plants and animals, for example, starch and glycogen, respectively. These glycans are polymers of glucose and are broken down during cellular respiration to release energy. The study of these energy-storage glycans is central to understanding metabolic processes.