פרוטאוגליקנים וגליקופרוטאינים מטריקס

Matrix proteoglycans are composed of several glycosaminoglycans chains covalently attached to a core protein. They are commonly found in the extracellular matrix or ECM and at the cell membrane.

In contrast, in glycoproteins, a protein core is covalently attached to oligosaccharide chains. They come in different forms and are usually found on the cell membrane, in the ECM, and in blood.

Cells communicate with other cells by secreting signaling proteins that travel through the dense ECM network to reach their designated cells.

The proteoglycans with multiple binding sites act as local reservoirs for vascular endothelial growth factors that are responsible for cell proliferation.

In this way, proteoglycans limit the diffusion of the growth factor, localizing their effect on nearby cells.

Proteoglycans also protect several signaling proteins from degradation by proteases.

Similarly, glycoproteins, such as integrins, serve as cell surface receptors for another glycoprotein called fibronectin. These two glycoproteins together play major roles in connecting cells with the ECM.