Human Proinsulin Serum & Plasma OneStep ELISA Kit

Human proinsulin is the single-chain polypeptide precursor of insulin, synthesized within the endoplasmic reticulum of pancreatic beta cells. It consists of the insulin A and B chains connected by a middle segment known as the C-peptide. The primary function of proinsulin is to facilitate the correct folding and formation of the critical disulfide bridges that stabilize the mature insulin molecule. Following its synthesis, proinsulin is transported to the Golgi apparatus and packaged into secretory granules, where it undergoes enzymatic cleavage by prohormone convertases PC1/3 and PC2. This proteolytic processing removes the C-peptide, resulting in the mature insulin molecule and the freed C-peptide, which are then co-secreted in equimolar amounts into the bloodstream upon glucose stimulation. While proinsulin itself possesses minimal biological activity compared to insulin, its circulating level serves as an important biomarker; elevated proinsulin is indicative of beta-cell stress and dysfunction, often observed in early Type 2 diabetes and insulin resistance. Furthermore, measurement of proinsulin and the proinsulin-to-insulin ratio is used clinically to assess beta-cell health and insulin secretory capacity.