Conjugated proteins are composed of an apoprotein and what non-protein component?

• A. Apoprotein and prosthetic group
• B. Apoprotein only
• C. Prosthetic group only
• D. Carbohydrate chains

Answer: (A)

Conjugated proteins need both a protein part and a non-protein component to be active. The non-protein piece is tightly bound and essential for function, and it’s called a prosthetic group. So the complete conjugated protein is the apoprotein plus a prosthetic group. Without the prosthetic group the protein part remains inactive, and the prosthetic group alone cannot carry out the protein’s specific function. While some proteins do have carbohydrate attachments (glycoproteins), the defining non-protein component in this context is the prosthetic group.