Extracellular matrix or glucocalyx

A large part of the cells of multicellular beings are covered by the extracellular matrix, composed of macromolecules secreted by the cell. It's formed by:

• Fibrous proteins.
  • The collagen. It is the most abundant and provides resistance.
  • Elastin. Provides elasticity. It is abundant in some structures such as ligaments, the walls of blood vessels or lung tissue.
• Proteoglycans.
• Structural glycoproteins. They form a network of elements that interact with the other components of the extracellular matrix and with those of the cell surface. Among them we can highlight.
  • Fibronectin. It collaborates in cell adhesion, appearing as long and insoluble fibrils.
  • Laminin. It is the first protein that allows cell adhesion during embryonic development.

Functions of the extracellular matrix

The glycocalyx has several functions:

• Protects the cell from possible physical and chemical injuries.
• Cell adhesion: fixes to cells that are part of tissues.
• It is related to the molecules of the extracellular matrix.
• It gives viscosity to cell surfaces, allowing moving cells to slide, such as blood cells.
• It has immune properties, since it allows the immune system to recognize and attack antigens. For example, the glycocalyx of erythrocytes represent the characteristic antigens of blood groups.
• Cancer defense: Changes in the glycocalyx of cancer cells allow the immune system to recognize and destroy them.
• Compatibility transplants: forms the basis for compatibility transfusion blood, of the grafted tissue and organ transplants, as is the responder and makes possible the recognition of compatible cells to add a tissue, organ, etc. to the body of some living being.
• Embryonic development: guides embryonic cells to their destinations in the body.
• It contributes to the recognition and fixation of certain substances that the cell will incorporate through phagocytosis or pinocytosis.