NEET PG Medical – 2019 – Question – 26
C-peptide seen in?
a) In Pre-proinsulin
b) In Proinsulin
c) As a combined entity with insulin after secretion
d) A gastrointestinal proactive molecul
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Correct Answer – B
Ans: B. In proinsulin
Synthesis of insulin:
- Synthesized as larger preprohormone (Pre-proinsulin) entering ER.
- Removal of 23 amino-acid signal peptide takes place.
- Converted to “Prohormone -Proinsulin”.
Proinsulin structure: - Made up A & B chain, connected by C-peptide/chain.
C-peptide – - Detached from granules before secretion.
- 90% – 97% insulin from B cells.
- Along with equimolar amounts of C-peptide.
