Proinsulin is a precursor of insulin that is synthesized in the β cells of the islet of Langerhans in the pancreas. 　

Most of the proinsulin synthesized in the rough endoplasmic reticulum of β cells is stored in the secretory granules. It is cleaved by prohormone converting enzyme (PC 2 and PC 3) and it is divided into insulin that consists of 21 amino-acid A chain, 30 amino-acid B chain and C-peptide that consists of 33 amino acids. It is then released in blood by a secretory stimulation such as glucose.

However, some proinsulin does not enter secretory granules and is subsequently released in blood as intact (full length) proinsulin without processing.

It is known that the ratio of proinsulin and insulin (P/I ratio) is an indicator of dysfunction of pancreatic β cells as the ratio of proinsulin becomes higher due to an abnormality of processing caused by the dysfunction of pancreatic β cells.

The P/I ratio is a valuable pancreatic β cell evaluation method that does not require a loading test as it can be measured using blood samples in fasting.

This CLEIA kit has a wide measurement range to measure intact proinsulin at low levels in fasting and at high levels after loading using only 10 μL sample.

The Intact Proinsulin (Mouse/Rat) CLEIA Kit is for the determination of Intact Proinsulin in mouse/rat Serum, EDTA-plasma and Heparin-Plasma. 

For research use only, not for use in diagnostic procedures.

More information: Intact Proinsulin (Mouse/Rat) CLEIA Kit