7.3 Glycoconjugates: Proteoglycans and Glycoproteins

Glycoconjugate

Biologically active molecule made up of an informational carbohydrate joined to a protein or lipid

What are 2 types of glycoconjugates?

Proteoglycans & glycoproteins

Proteoglycans

Macromolecules only found at the cell surface or ECM with 1+ sulfated glycosaminoglycan chains
Include the heparan sulfate family
Only has sulfated glycosaminoglycan chains covalently linked to Ser

Proteoglycan unit

Core protein with covalently attached glycosaminoglycans Tetrasaccharide linker connects to glycosaminoglycan to a Ser residue of the protein

What are 2 families of membrane heparan sulfate proteoglycans?

Syndecans and glypicans

Syndecans

Single transmembrane domain and an extracellular domain bearing 3-5 chains of heparan sulfate and chondroitin sulfate

Glypicans

Attached to the membrane by a GPI anchor (a glycosylated derivative of the membrane lipid phosphatidylinositol