A glycoprotein is part of an extremely diverse group of linked amino acid and carbohydrate chains. Glycoproteins are found throughout nature and have a similarly diverse range of functions. They are one of two glycoconjugates-the other group is composed of glycolipids. Glycoprotein examples include fibrillins, mucins, tumor necrosis factor, and membrane glycoproteins on body cells, bacteria, and viruses.