Insulin in Pro-hormone Form

Introduction:
Insulin is a hormone produced by the beta cells of the pancreas. It plays a crucial role in regulating blood glucose levels. The primary form of insulin is synthesized as a precursor molecule called pro-insulin. Pro-insulin contains an extra stretch called C-peptide.

Explanation:
The C-peptide is a peptide chain that connects the A-chain and B-chain of pro-insulin. It is formed during the post-translational processing of pro-insulin into insulin. The C-peptide is cleaved off during this process, resulting in the formation of mature insulin.

Functions of C-peptide:
1. Structural function: The C-peptide helps to maintain the structure of pro-insulin by connecting the A-chain and B-chain. This structural stability is essential for proper folding and function of pro-insulin.
2. Insulin synthesis: The C-peptide is cleaved off during the conversion of pro-insulin into insulin. This cleavage is necessary for the formation of the mature insulin molecule, which is biologically active.
3. Secretion regulation: C-peptide has been found to play a role in regulating the secretion of insulin from beta cells. It helps to maintain the balance between insulin synthesis and secretion, ensuring optimal glucose homeostasis.
4. Physiological effects: Although C-peptide was initially considered biologically inert, recent studies have shown that it may have some physiological effects. It has been proposed to have beneficial effects on blood vessel function, kidney function, and nerve function.

Conclusion:
The presence of C-peptide in pro-insulin is crucial for the proper synthesis and secretion of insulin. While insulin is the biologically active hormone responsible for regulating blood glucose levels, C-peptide also has important functions in maintaining the structure of pro-insulin and potentially exerting physiological effects.