The Insulin-like Growth Factor 1 (IGF-1) Receptor is a transmembranereceptorthat is activated by IGF-1and by the related growth factor IGF-II. It belongs to the large class of tyrosine kinasereceptors. This receptor mediates the effects of IGF-1, which is a polypeptide protein hormone similar in molecular structure to insulin. IGF-1 plays an important role in growth and continues to have anabolic effects in adults - meaning that it can induce hypertrophy of skeletal muscleand other target tissues.IGF-1R (Insulin-like Growth Factor-1 Receptor) consists of alpha- and Beta-subunits, which are disulfide-linked in a Beta-alpha-alpha-Beta configuration in the mature receptor. The alpha-subunit is completely extracellular, while the Beta-subunit spans the membrane and the intracellular portion has intrinsic tyrosine kinase activity Synonyms: Insulin-like growth factor 1 receptor, EC 2.7.10.1, Insulin-like growth factor I receptor, IGF-I receptor, CD221 antigen, CD221, IGFIR, JTK13, MGC18216, MGC142170, MGC142172