GAGs (glycosaminoglycans) are important for the ECM due to?

Glycosaminoglycans (GAGs) play a crucial role in the extracellular matrix (ECM) primarily due to their ability to attract and retain water, behaving like a hydrogel. This characteristic is essential because it provides the ECM with resistance to compressive forces, which is vital in maintaining tissue integrity and functionality. By serving as a scaffold that can support the mechanical loads that tissues experience, GAGs help in cushioning cells and allowing for the proper distribution of mechanical stress throughout the tissue. This property is particularly important in tissues that are subjected to dynamic forces, such as cartilage in joints.

While GAGs do interact with various cell types and aid in cellular processes, their defining feature is not that they create ecosystems for other cells or that they store fat, which are attributes associated with other components of tissues. Instead, their hydrophilic nature is what endows them with the capacity to maintain hydration and structural resilience in the ECM.