Final answer:
Hyaluronic acid is the glycosaminoglycan (GAG) that provides protection and acts as a shock absorber in the extracellular matrix. It forms part of the proteoglycans that help maintain the structural integrity of tissues, allow communication between cells, and protect against compression and external stresses.
Step-by-step explanation:
The extracellular matrix performs a variety of functions, including mediation of interactions between cells. Hyaluronic acid is a glycosaminoglycan (GAG), which provides protection and acts as a shock absorber. Glycosaminoglycans like hyaluronic acid are usually linked to proteins to form proteoglycans. These proteoglycans, along with fibrous proteins like collagen, provide structural support, facilitate cell-cell communication, and help in resisting compression by forming hydrated gels. This is particularly essential in various types of connective tissues where the extracellular matrix is extensive and gives tissues distinct properties.
Furthermore, the extracellular matrix plays a crucial role in protecting animal cells from physical stresses and aids in the transmission of signals from the external environment to the interior of the cell. Pathogens such as Streptococcus pyogenes often utilize the extracellular matrix to attach and establish infections in the host, highlighting the importance of components like fibronectin and integrin proteins that connect the extracellular matrix to cell membranes and facilitate such interactions.