And number four it actually functions to move molecules through the extracellular matrix. Now one example of a well studied proteoglycan that we know a lot about is aggregate. And aggregate is found in the extracellular matrix of connective tissues such as Cartilage. And this is what we're going to focus on in this lecture. So if we examine Cartilage we have many different types of cells and surrounding the cells we have the extracellular matrix. Now the major component of Carthage is collagen.