Catalytic activity:ATP + a [protein]-L-tyrosine = ADP + a [protein]-L-tyrosine phosphate. ,Disease:Defects in IGF1R may be a cause in some cases of resistance to insulin-like growth factor 1 (IGF1 resistance) [MIM:270450]. IGF1 resistance is a gowth deficiency disorder characterized by intrauterine growth retardation and poor postnatal growth accompanied with increased plasma IGF1. ,enzyme regulation:Autophosphorylation activates the kinase activity. ,Function:This receptor binds insulin-like growth factor 1 (IGF1) with a high affinity and IGF2 with a lower affinity. It has a tyrosine-protein kinase activity , which is necessary for the activation of the IGF1-stimulated downstream signaling cascade. When present in a hybrid receptor with INSR , binds IGF1. PubMed:12138094 shows that hybrid receptors composed of IGF1R and INSR isoform Long are activated with a high affinity by IGF1 , with low affinity by IGF2 and not significantly activated by insulin , and that hybrid receptors composed of IGF1R and INSR isoform Short are activated by IGF1 , IGF2 and insulin. In contrast , PubMed:16831875 shows that hybrid receptors composed of IGF1R and INSR isoform Long and hybrid receptors composed of IGF1R and INSR isoform Short have similar binding characteristics , both bind IGF1 and have a low affinity for insulin. ,online information:IGF-1 receptor entry ,PTM:Phosphorylation of Tyr-980 is required for IRS1- and SHC1-binding. ,PTM:The cytoplasmic domain of the beta subunit is autophosphorylated on tyrosine residues in response to insulin-like growth factor I (IGF I) . ,similarity:Belongs to the protein kinase superfamily. Tyr protein kinase family. Insulin receptor subfamily. ,similarity:Contains 1 protein kinase domain. ,similarity:Contains 3 fibronectin type-III domains. ,subunit:Tetramer of 2 alpha and 2 beta chains linked by disulfide bonds. The alpha chains contribute to the formation of the ligand-binding domain , while the beta chain carries the kinase domain. Interacts with PIK3R1 and with the PTB/PID domains of IRS1 and SHC1 in vitro when autophosphorylated on tyrosine residues. Forms a hybrid receptor with INSR , the hybrid is a tetramer consisting of 1 alpha chain and 1 beta chain of INSR and 1 alpha chain and 1 beta chain of IGF1R. ,tissue specificity:Found as a hybrid receptor with INSR in muscle , heart , kidney , adipose tissue , skeletal muscle , hepatoma , fibrobasts , spleen and placenta (at protein level) . Expressed in a variety of tissues. ,
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