Preproinsulin

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Preproinsulin is the primary translation product of the insulin gene. It is a peptide of 110 amino acids. Preproinsulin is a precursor processed by proteases to proinsulin by removal of the signal peptide and then to insulin by removal of the connecting peptide (C-peptide) in order to be biologically active.

Almost no preproinsulin exists in the cell, since removal of the signal peptide is not a separate step but closely linked to translation into the endoplasmic reticulum (ER). For the same reason, preproinsulin is rarely used unlike insulin, the mature product, and proinsulin, a stable ER intermediate.

See also

• insulin
• signal peptide, signal peptide peptidase
• proinsulin
• proprotein convertase 1, proprotein convertase 2