7.3 Glycoconjugates

Question 1

What is a glycoconjugate?

Answer 1

Molecule Consisting of an Informational Carbohydrate Joined to a Protein or Lipid.

Question 2

Mention Different Types of Glycoconjugates

Answer 2

Proteoglycans, Glycoproteins, Glycolipids ad Glycosphingolipids, Sulfate Proteoglycans

Question 3

What are Glycoproteins and Proteoglycans and Where Are They Found?

Answer 3

Glycoproteins: oligosaccharide(s) bound to protein. Found on the plasma membrane, in the ECM, and some organelles. Oligosaccharides are heterogenous and informational (recognition).

Proteoglycans: Sulfated glycoseaminoglycan chain(s) bound to membrane or secreted protein. Major component of ECM.

Question 4

What Are Glycolipids and Glycosphingolipids and Where Are They Found?

Answer 4

Glycolipids are components of the plasma membrane, where the hydrophilic heads are oligosaccharides.

Glycosphingolipids are a class of glycolipids, whith a specific backbone (sphingolipids). These are abundant in neurons, and function in recognition and signal transduction.

Question 5

Mention the Two Families of Membrane Heparan Sulfate Proteoglycans and (generally) Their Structure

Answer 5

Syndecans have a transmembrane domain and a extracellular domain with heparan or chondroitin sulfate.
Glypicans are attached to the membrane through a GPI anchor (glycosilated derivative of phosphatidylinsolitol).
These are involved in proteoglycan “shedding” to quickly change the surface structure of the cell.

Question 6

What Is the Purpose of Protein-bound Oligosaccharides?

Answer 6

Oligosaccharides are structurally diverse and complex molecules. They can influence the protein folding and stability, and provide a wide array of recognizable information by proteins or targering of new proteins.