So inside our body we have many different types of glycoproteins and generally speaking, glycoproteins have a wide range of function. So what I'd like to do in this lecture is focus on several important glycoproteins that exist inside our body and see how by adding the sugar component onto the protein, we give the protein the ability to carry out some specific type of process. Now at the end of the lecture I'd also like to discuss an example of a disease known as the eye cell disease that exists in humans that basically demonstrates the importance of protein glycosylation. So let's begin by discussing a category of glycoproteins known as mucins. Now mucins, as we'll see in just a moment, are the major constituents, the major components of the mucus membranes that exist inside our body. So the mucous membranes can be found in the nasal cavity, in our air passageways, the bronchioles and so forth.