CHAPTER 20: GLYCOPROTEINS AND GLYCOLIPIDS

Macromolecules found in most organisms that are associated with several important physiologic processes. They have covalently linked oligosaccharide chains and include enzymes, structural proteins, hormones, immunoglobulins, receptors, and transport proteins.

Glycoproteins

Chains of carbohydrates attached to proteins through N-glycosidic or O-glycosidic bonds. They encode biologic information and can range from 1% to over 80% of the weight of glycoproteins.

Oligosaccharide chains

Carbohydrate-binding proteins that agglutinate cells or precipitate glycoconjugates. They can be glycoproteins and participate in cell-cell interactions in pathologic conditions such as inflammation and cancer metastasis.

Lectins

Glycoproteins distributed on the surfaces of epithelial cells that help lubricate and protect respiratory, gastrointestinal, and reproductive tracts. They have a high viscosity and are sometimes called mucoproteins.

Mucins

Extracellular coat surrounding ovulated eggs. O-linked oligosaccharides attached to the glycoprotein ZP3 in the coat are recognized by sperm receptors, triggering fertilization.

Zona pellucida

Carbohydrate-containing lipids with a sphingosine backbone. They are important in intercellular communication and can be found in plasma membranes.

Glycolipids

Inherited disorders of lysosomal hydrolase enzymes that result in the accumulation of gangliosides and glycolipids within neurons and glia throughout the nervous system. They can lead to demyelinating disorders and leukodystrophies.

Ganglioside storage diseases

Diseases characterized by the loss of phospholipids and sphingolipids from neurons in the brain and spinal cord. They can result in progressive paraparesis and pelvic limb ataxia.

Demyelinating disorders

Diseases characterized by the accumulation of glycolipids and other substrates within lysosomes of neurons and glia. They

Lysosomal storage disorders