What is true about a glycoprotein?

What is true about a glycoprotein?

• A. It is a protein with attached carbohydrate groups
• B. It is a carbohydrate with attached protein groups
• C. It has no carbohydrates
• D. It is only lipid bound

Answer: (A)

Glycoproteins are proteins that have carbohydrate groups covalently attached. The carbohydrate portion, or glycan, is linked to specific amino acids in the protein—most often N-linked to asparagine or O-linked to serine/threonine. This modification helps with protein folding and stability, and it also plays key roles in cell signaling, recognition, and interactions, which is why many secreted and membrane proteins turn out to be glycoproteins, such as antibodies and mucins. They’re not simply carbohydrates with attached proteins, they do contain carbohydrates, and they aren’t defined by lipid binding alone. They are also distinct from proteoglycans, which have much larger carbohydrate chains attached.

Glycoproteins are proteins that have carbohydrate groups covalently attached. The carbohydrate portion, or glycan, is linked to specific amino acids in the protein—most often N-linked to asparagine or O-linked to serine/threonine. This modification helps with protein folding and stability, and it also plays key roles in cell signaling, recognition, and interactions, which is why many secreted and membrane proteins turn out to be glycoproteins, such as antibodies and mucins. They’re not simply carbohydrates with attached proteins, they do contain carbohydrates, and they aren’t defined by lipid binding alone. They are also distinct from proteoglycans, which have much larger carbohydrate chains attached.