During the processing of the prohormone “proinsulin” into the mature “insulin”
(a) C-peptide is added to proinsulin
(b) C-peptide is removed from proinsulin
(c) B-peptide is added to proinsulin
(d) B-peptide is removed from proinsulin.
Answer (b) : Human insulin is made up of 51 amino acids arranged in two polypeptide chains, A having 21 amino acids and B with 30 amino acids. The hormone develops from a storage product called pro-insulin. Pro-insulin has three chains, A, B and C. C – chain with 33 amino acids is removed prior to insulin formation. This C peptide is not present in the mature insulin and is removed during maturation into insulin.
