Plasma proteins have vital roles in the body ranging from maintaining osmolarity to transport of hormones. Certain statements are given below for the functions of selected plasma proteins: A. Von Willebrand factor is normally synthesized in the liver. B. Ceruloplasmin is a copper carrier protein. C. Genetic deficiency of α1 ‐antiproteinase causes emphysema. D. Most plasma proteins including albumin are covalently glycosylated. E. α1 ‐acid glycoprotein (AGP) level increases during body’s response to inflammation. Which one of the following represents all correct combination of statements?
B, C and E only
Plasma Protein Functions Analysis
Plasma proteins perform many essential functions in the body, including maintaining osmotic pressure, transporting substances, and participating in immune and coagulation processes. Let's evaluate each statement provided regarding specific plasma proteins.
Von Willebrand Factor Synthesis
Statement A says that Von Willebrand factor is normally synthesized in the liver. Von Willebrand factor (vWF) is a large glycoprotein involved in blood clotting. It is primarily synthesized by endothelial cells (cells lining blood vessels) and megakaryocytes (precursors of platelets). The liver is the primary site of synthesis for many other coagulation factors and plasma proteins, but not vWF.
Therefore, statement A is incorrect.
Ceruloplasmin as Copper Carrier
Statement B says that Ceruloplasmin is a copper carrier protein. Ceruloplasmin is indeed the major copper-carrying protein in the blood plasma. It also plays a role in iron metabolism, oxidizing ferrous iron ($ \text{Fe}^{2+} $) to ferric iron ($ \text{Fe}^{3+} $), which is required for binding to transferrin. This statement accurately describes a primary function of ceruloplasmin.
Therefore, statement B is correct.
Alpha1-Antiproteinase Deficiency and Emphysema
Statement C says that genetic deficiency of $ \alpha_1 \text{-antiproteinase} $ causes emphysema. $ \alpha_1 \text{-antiproteinase} $ (also known as $ \alpha_1 \text{-antitrypsin} $) is a protein that inhibits various enzymes, particularly elastase, which is released by neutrophils in the lungs. Elastase can break down lung tissue. A deficiency in $ \alpha_1 \text{-antiproteinase} $ leads to excessive elastase activity, resulting in the destruction of alveolar walls and the development of emphysema.
Therefore, statement C is correct.
Glycosylation of Plasma Proteins
Statement D says that most plasma proteins including albumin are covalently glycosylated. Glycosylation is the process of adding carbohydrate chains to a protein. Many plasma proteins, such as immunoglobulins, transferrin, and $ \alpha_1 \text{-acid glycoprotein} $, are glycoproteins, meaning they are glycosylated. However, albumin, which is the most abundant plasma protein, is notably not glycosylated under normal conditions. Therefore, stating that most plasma proteins including albumin are glycosylated is inaccurate.
Therefore, statement D is incorrect.
Alpha1-Acid Glycoprotein and Inflammation
Statement E says that $ \alpha_1 \text{-acid glycoprotein} $ (AGP) level increases during body’s response to inflammation. $ \alpha_1 \text{-acid glycoprotein} $ is known as an acute-phase protein. Acute-phase proteins are a class of proteins whose concentrations in the blood plasma change in response to inflammation, infection, or trauma. AGP is a positive acute-phase protein, meaning its concentration increases significantly during such conditions.
Therefore, statement E is correct.
Summary of Statement Analysis
Based on the analysis:
- Statement A: Von Willebrand factor is normally synthesized in the liver. - Incorrect (Synthesized by endothelial cells and megakaryocytes)
- Statement B: Ceruloplasmin is a copper carrier protein. - Correct
- Statement C: Genetic deficiency of $ \alpha_1 \text{-antiproteinase} $ causes emphysema. - Correct
- Statement D: Most plasma proteins including albumin are covalently glycosylated. - Incorrect (Albumin is not glycosylated)
- Statement E: $ \alpha_1 \text{-acid glycoprotein} $ (AGP) level increases during body’s response to inflammation. - Correct
The correct statements are B, C, and E.
Identifying the Correct Combination
We need to find the option that lists only the correct statements (B, C, and E).
- Option 1: A, B and C only (Includes A which is incorrect)
- Option 2: B, C and D only (Includes D which is incorrect)
- Option 3: B, C and E only (Includes only B, C, and E which are correct)
- Option 4: A, D and E only (Includes A and D which are incorrect)
The combination that includes all correct statements and no incorrect statements is B, C, and E.
| Statement | Protein | Claim | Correctness |
|---|---|---|---|
| A | Von Willebrand factor | Synthesized in liver | Incorrect |
| B | Ceruloplasmin | Copper carrier | Correct |
| C | $ \alpha_1 \text{-antiproteinase} $ | Deficiency causes emphysema | Correct |
| D | Most plasma proteins (incl. albumin) | Glycosylated | Incorrect |
| E | $ \alpha_1 \text{-acid glycoprotein} $ (AGP) | Increases in inflammation | Correct |
The correct combination of statements is B, C, and E.
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