CBSE Class 11-science Answered
Differences between glycoproteins and proteoglycans:
Point of Difference |
Glycoproteins |
Proteoglycans |
Structure |
Oligosaccharide (carbohydrate) chains are covalently attached to a polypeptide side chain |
Glycosaminoglycan (GAG) chain(s) are attached to a polypeptide side chain |
Nature of Chains |
Oligosaccharide chains are short, branched, and may or may not be negatively charged. |
Glycosaminoglycan chains are long, linearised, and negatively charged because of the presence of sulphate and uronic acid functional groups. |
Non-protein Content |
10 - 15% by weight |
50 - 60% by weight |
Subtypes |
Broadly categorised as N-linked and O-linked saccharides. |
Classification depends on the nature of the GAG chains. |
Location |
Found on the cell surface with the carbohydrate chains placed outside the cell |
Found in the connective tissues. |
Function |
Act as integral membrane proteins, and play a role in cell-cell recognition and signaling |
Provide structural support and mechanical strength to the extracellular matrix, play a role in the modulation of cell growth processes, and provide padding in joints. |
Examples |
ABO blood group antigens Hormones like follicle stimulating hormone(FSH) |
Aggrecan Perlecan |
The sample can be tested for the presence of carbohydrate or protein content in order to judge whether the given sample is of glycoproteins or proteoglycans.
In proteoglycans, the carbohydrate moiety dominates, constituting about 95% or more of the mass of the complex.
In gycoproteins, the protein constitutes a larger fraction, generally 50% or more of the total mass.