Proinsulin intact (mouse/rat) ELISA

Original article #27706 Proinsulin is a precursor of insulin that is synthesized in the beta cells of the islet of Langerhans in the pancreas. Most of the proinsulin synthesized in the rough endoplasmic reticulum of beta cells is stored in the secretory granules. Proinsulin is cleaved by prohormone converting enzyme (PC) 1/3 at the junction of the C-peptide with the B-chain of insulin, subsequently it is cleaved by PC2 at the junction of the C-peptide with the A-chain of insulin, consequently it is divided into insulin that consists of a 21 amino-acid alpha-chain and a 30 amino-acid beta-chain and c-peptide that consists of 33 amino acid. It has been considered that the conversion rate from proinsulin to insulin in type 2 diabetes patients decreases due to dropping down of PC1/3 enzymatic activity by abnormal function of pancreatic beta cells. Thus, intact proinsulin level in blood or the ratio of intact proinsulin and insulin (P/I ratio) can be considered to become a potential biomarker that reflects functional change of the PC1/3 activity at pancreatic beta cells. Especially, It has been known that the P/I ratio is a valuable pancreatic beta cell evaluation method that does not require a loading test as it can be measured using blood samples in fasted state. This ELISA kit can be used for measuring intact proinsulin, not including cleaved intermediate products, in mouse and rat samples.