Glykokalixlag

Glykokalixlag, commonly referred to as the glycocalyx layer, is a carbohydrate-rich coating that covers the exterior of many animal cells. It is formed mainly by glycoproteins, proteoglycans, and glycolipids embedded in the plasma membrane, together with secreted mucins in several mucosal epithelia. The layer is attached to the membrane by transmembrane proteins and can vary in thickness and composition between cell types and physiological conditions.

Composition and structure vary, but the core components are glycosylated proteins and lipids that protrude from the cell surface. In epithelial tissues, secreted mucins contribute a hydrated, viscous layer. The glycocalyx is dynamic, constantly remodeled by cellular and environmental factors, and its physical properties influence how the cell interacts with its surroundings.

Location and roles are broad. It is present on most animal cells and is particularly prominent at mucosal surfaces and in the vascular endothelium, where it can form a protective, lubricating barrier. Functions include protection of the plasma membrane from mechanical and chemical stress, facilitation of cell and matrix interactions, mediation of cell signaling, and regulation of immune recognition. The glycocalyx also participates in mechanotransduction, helping cells sense shear forces and other mechanical cues.

Clinical and biological relevance varies. Alterations or degradation of the endothelial glycocalyx are associated with vascular dysfunction and inflammation, while remodeling of the glycocalyx on cancer cells can influence adhesion and metastasis. In bacteria, a related concept is the capsule or slime layer, a polysaccharide exterior that contributes to protection and immune evasion.