C-peptide

Human C peptide is a straight chain consisting of 31 amino acids and a molecular weight of 3020. C peptide and insulin are secreted from B cells into the blood with equal molecular weight. It is not taken up by liver cells, and is mainly metabolized by the kidneys and excreted from the kidneys. C-peptide has no biological activity, does not bind to receptors on cell membranes, and is not degraded. Its half-life is 3 to 4 times that of insulin.