Pro-insuline consists of

Options

A. A-peptide
B. A and B peptide
C. A, B and C peptides
D. Only C-peptide

Answer

To answer the question "Pro-insulin consists of," we will break down the information step by step:

### Step-by-Step Solution:

1. **Understanding Pro-insulin**:
- Pro-insulin is a precursor to insulin, which means it is an inactive form that is converted into the active hormone insulin.

2. **Location of Production**:
- Pro-insulin is produced in the beta cells of the islets of Langerhans in the pancreas.

3. **Genetic Encoding**:
- In humans, pro-insulin is encoded by the INS gene.

4. **Composition of Pro-insulin**:
- Pro-insulin consists of three distinct parts: the A-peptide, B-peptide, and C-peptide.
- Specifically, it is made up of 86 amino acid residues, which include these three components.

5. **Structure of Pro-insulin**:
- The A-peptide and B-peptide are connected by the C-peptide.
- The proper arrangement of these peptides is crucial for the correct folding and function of the mature insulin molecule.

6. **Conclusion**:
- Therefore, the correct answer to the question is that pro-insulin consists of A-peptide, B-peptide, and C-peptide.

### Final Answer:
- Pro-insulin consists of **A-peptide, B-peptide, and C-peptide** (Option C).

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