This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET 2019, Subject name: Physiology
[{'content': 'C- peptide is seen:- \nSelect and explain. \nA. In pre-proinsulin, B. In Proinsulin, C. As a combined entity with insulin after secretion, D. As a gastrointestinal proactive molecule', 'role': 'user'}, {'content': 'Answer: B \nExplanation: - Insulin is synthesized in BETA- cells of pancreas by usual cell machinery for protein synthesis. - Beginning with translation of insulin RNA by ribosomes attached to E.R to form pre proinsulin. - Pre proinsulin is cleaved in E.R to form pro-insulin. - Insulin & C peptide are packaged in secretory granules & secreted in equimolar amounts. - So, c - peptide levels can be measured by radioimmunoassay in insulin-treated diabetic patients to determine how much of their own natural insulin they are still producing', 'role': 'assistant'}]