| Insulin-like growth factor 1 is a peptide structurally related to proinsulin and has a primary role in promoting skeletal muscle differentiation and growth. |
| Insulin is derived from a larger single chain precursor protein, proinsulin which contains 81 amino acids and three disulfide bonds. |
| Following cleavage of the 24 amino acid signal peptide the protein folds into proinsulin. |
| Insulin is synthesized as a precursor, preproinsulin, and after removal of the signal peptide, proinsulin folds to form the correct tertiary structure. |
| Unlike the single chain precursor of insulin, proinsulin, this new construct retains up to 40 per cent of insulin activity. |
| Recent studies have reported an increase in intact proinsulin levels in insulin-resistance individuals. |
