Glyconjugates and Proteins Overview

Glyconjugates

• Sugars are linked to proteins or lipids forming glycoconjugates.
• Proteoglycans: Large molecules found on cell surfaces or within the extracellular matrix. They consist of a protein core with long chains of glycosaminoglycans (GAGs) attached.
• Glycoproteins: Proteins with one or more oligosaccharide chains linked to them.
• Glycolipids: Lipids with oligosaccharide chains attached to their polar head group.

Proteins

• Proteoglycans: A major component of the extracellular matrix, they form aggregates with hyaluronic acid.
• Integrins: Proteins that link the extracellular matrix and cytoskeleton, enabling communication between the cell exterior and interior.
• Collagen, Fibronectin, Elastin, and Proteoglycans: These components work together to create the extracellular matrix, providing structural support and organization to tissues.
• Actin Filaments: Form the cytoskeleton, providing structure and shape to cells. These filaments also connect to integrins, further linking the extracellular matrix and the cell interior.

Glycoproteins

• Glycoproteins: Found on the exterior of cell membranes, they play various roles.
• Glycoforin A: A glycoprotein found in red blood cell membranes.
• Hormones (FSH, LH): Examples of glycoproteins that function as hormones.
• Immunoglobulins: Antibodies that are also glycoproteins.

Glycolipids

• Glycolipids: Membrane lipids with oligosaccharide chains as a key component of their polar head groups, interacting with proteins on the membrane's exterior.
• Gangliosides: A specific type of glycolipid with a complex carbohydrate structure, important for cell recognition and signaling.
• Blood Groups: Glycolipids play a crucial role in determining blood types.

Lectins

• Lectins: Proteins that bind specifically to sugar sequences, found on cell membranes.
• Influenza Virus: Recognizes host cell sugars using lectins to gain entry.
• Herpes Virus: Also uses lectins for binding and infection.
• P-selectins: Lectins that slow down lymphocytes, allowing the immune system to target inflamed blood vessels.

Toxin

• Cholera toxin: Recognizes oligosaccharides of gangliosides on enterocytes, leading to the severe symptoms of cholera.

This quiz explores the fascinating world of glyconjugates and proteins, focusing on their structures and functions within the extracellular matrix. It covers key components such as proteoglycans, glycoproteins, and collagen, as well as their roles in cellular organization and communication. Test your knowledge of these essential biomolecules!