There are two kinds of IGF receptors based on their relative affinities for IGF1 versus IGF2. The IGF1 receptor prefers IGF1 over IGF2 and weakly binds insulin. IGF1 receptor is a disulfide-linked heterotetrameric transmembrane protein consisting of
IGF-I and -II signal through the IGF-I Receptor, which is homologous to the Insulin Receptor. The high-affinity IGF-II Receptor does not play a direct role in signaling, but regulates the concentration of free IGF-II. The IGFs are involved in skeleta