Résumé
The insulin-like growth factors IGFl and IGF2 are mitogenic polypeptides which are structurally and functionally homologous to the hormone insulin. Both single chain peptides play important roles in pathways regulating growth and development (1, 2). Their action is mediated by specific interactions with cell surface receptors and is further modified by at least six different IGF-binding proteins. Two IGF receptors have been identified. The type-1 receptor has a higher affinity for IGFl than for IGF2 and is related to the insulin receptor. The type-2 receptor, which is also a receptor for mannose-6-phosphate, binds IGF2 with high affinity, but is structurally distinct from the type-1 and insulin receptors. IGFl and IGF2 mediate their effects on growth and development through the type-1 receptor (3).