Role of Glycoproteins
- Carbohydrates and polypeptides can combine, via covalent bonds, to make structures called glycoproteins
- These are classed as proteins
- Glycoproteins, along with another group of molecules called glycolipids, form part of the structure of cell surface membranes
- They act as receptor molecules in processes such as
- Cell recognition and identification
- Receptors for cell signalling molecules such as hormones and neurotransmitters
- Endocytosis
- Cell adhesion and stabilisation
Glycoproteins and ABO blood types
- Glycoproteins can act as antigens which can identify cells as either "self" or "non-self"
- Cells that are recognised as non-self will trigger an immune response within the organism
- A person's blood type is determined by the glycoprotein antigens on the surface of their red blood cells
- Blood type A individuals have type A glycoprotein antigens
- Blood type B individuals have type B glycoprotein antigens
- Blood type AB individuals have both types of glycoprotein antigens
- Blood type O individuals have neither
- The presence of antibodies within an individual can create an interaction with the glycoproteins if blood of the wrong type enters their body
- E.g. a person with Type A antigens on their red blood cells will have antibodies in their blood against type B antigens
- This can cause fatal issues during blood transfusions if the incorrect blood type is given, as the antibodies cause the incorrect antigens (from the transfused blood) to clump together, blocking blood vessels
Blood Types and their Antigens and Antibodies Table
| Blood type A | Blood type B | Blood type AB | Blood type O | |
| Red blood cell surface antigens | Type A | Type B | Type A & B | None |
| Antibodies present in plasma | Anti-B | Anti-A | None | Anti-B & anti-A |
| Blood groups that may be used for transfusion | A & O | B & O | A, B, AB, O | O |