Gene Summary: This receptor binds insulin-like growth factor with a high affinity. It has tyrosine kinase activity. The IGF1R plays a critical role in transformation events. Cleavage of the precursor generates alpha and beta subunits. IGF1R is highly overexpressed in most malignant tissues where it functions as an anti-apoptotic agent by enhancing cell survival. General information above from NCBI
Catalytic activity: ATP + a [protein]-L-tyrosine = ADP + a [protein]-L-tyrosine phosphate.
Enzyme regulation: Activated by autophosphorylation at Tyr-1165, Tyr-1161 and Tyr-1166 on the kinase activation loop; phosphorylation at all three tyrosine residues is required for optimal kinase activity. Inhibited by MSC1609119A-1, BMS-754807, PQIP, benzimidazole pyridinone, isoquinolinedione, bis-azaindole, 3-cyanoquinoline, 2,4-bis-arylamino-1,3-pyrimidine, pyrrolopyrimidine, pyrrole-5-carboxaldehyde, picropodophyllin (PPP), tyrphostin derivatives. While most inhibitors bind to the ATP binding pocket, MSC1609119A-1 functions as allosteric inhibitor and binds close to the DFG motif and the activation loop.
Subunit structure: 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. Interacts with ARRB1 and ARRB2. Interacts with GRB10. Interacts with GNB2L1/RACK1. Interacts with SOCS1, SOCS2 and SOCS3. Interacts with 14-3-3 proteins. Interacts with NMD2. Interacts with MAP3K5. Interacts with STAT3.
Subcellular location: Membrane; Single-pass type I membrane protein.
Tissue specificity: Found as a hybrid receptor with INSR in muscle, heart, kidney, adipose tissue, skeletal muscle, hepatoma, fibroblasts, spleen and placenta (at protein level). Expressed in a variety of tissues. Overexpressed in tumors, including melanomas, cancers of the colon, pancreas prostate and kidney.
Post-translational: Autophosphorylated on tyrosine residues in response to ligand binding. Autophosphorylation occurs in trans, i.e. one subunit of the dimeric receptor phosphorylates tyrosine residues on the other subunit. Autophosphorylation occurs in a sequential manner; Tyr- 1165 is predominantly phosphorylated first, followed by phosphorylation of Tyr-1161 and Tyr-1166. While every single phosphorylation increases kinase activity, all three tyrosine residues in the kinase activation loop (Tyr-1165, Tyr-1161 and Tyr-1166) have to be phosphorylated for optimal activity. Can be autophosphorylated at additional tyrosine residues (in vitro). Autophosphorylated is followed by phosphorylation of juxtamembrane tyrosines and C-terminal serines. Phosphorylation of Tyr-980 is required for IRS1- and SHC1-binding. Dephosphorylated by PTPN1 (By similarity).
Polyubiquitinated at Lys-1168 and Lys-1171 through both 'Lys- 48' and 'Lys-29' linkages, promoting receptor endocytosis and subsequent degradation by the proteasome. Ubiquitination is facilitated by pre-existing phosphorylation.
Involvement in disease: A disorder characterized by intrauterine growth retardation, poor postnatal growth and increased plasma IGF1 levels. Note=The disease is caused by mutations affecting the gene represented in this entry.
Sequence similarity: Belongs to the protein kinase superfamily. Tyr protein kinase family. Contains 3 fibronectin type-III domains.
Contains 1 protein kinase domain.
General information above from UniProt