Eukaryotic initiation factor 4E binding protein 1 (4E-BP1), also known as PHAS, is a ~20 kDa member of a family of eIF4E-binding proteins whose binding affinity to eIF4E is regulated by its phosphorylation. It inhibits cap-dependent translation by binding to eIF4E on the same site that overlaps the binding site for eIF4G, preventing its binding to the latter and eventually leading to an increase in mRNA translation. The phosphorylation of 4E-BP1 is critical in determining cell fate by controlling translation initiation and apoptotic potency. 4E-BP1 is hyperphosphorylated in response to several external stimuli including hormones, growth factors, mitogens, cytokines and G-protein–coupled receptors and in response to stress conditions including nutrient deprivation. The phosphorylation of these sites is believed to occur in an orderly fashion where phosphorylation of threonine 37 and 46 by FRAP/mTOR is a priming step for subsequent phosphorylation of 4E-BP1 at the carboxy-terminal sites. Under normoxic conditions, increased VEGF expression, resulting from inhibition of 4E-BP1, contributes to efficient angiogenesis and metastatic brain growth through activated integrin alphav beta3.
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Protein Aliases: 4E-BP1; 4EBP1; eIF4E-binding protein 1; EIF4EBP1; Eukaryotic translation initiation factor 4E binding protein 1; Eukaryotic translation initiation factor 4E-binding protein 1; Insulin-stimulated EIF-4E binding protein PHAS-I; P/OKCL.6; PHAS-1; PHAS-I; Phosphorylated heat- and acid-stable protein regulated by insulin 1
Gene Aliases: 4E-BP1; 4EBP1; AA959816; BP-1; EIF4EBP1; PHAS-I