Eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) (4E-BP1)

Eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) is a key regulatory protein that controls the initiation of protein synthesis by sequestering the eukaryotic initiation factor 4E (eIF4E) (UniProt P60866). Under normal physiological conditions, 4E-BP1 is a primary substrate of the mechanistic target of rapamycin complex 1 (mTORC1) (PubMed: 23414311). When mTORC1 is active, it phosphorylates 4E-BP1 at multiple residues, causing it to release eIF4E and allowing the assembly of the eIF4F complex, which is essential for cap-dependent translation (PubMed: 21670308). In many cancers, the mTORC1/4E-BP1 axis is hyperactivated, leading to the preferential translation of mRNAs involved in cell cycle progression, survival, and angiogenesis (PubMed: 25824306). Therapeutic strategies often focus on inhibiting mTORC1 with drugs like Sirolimus or Everolimus to prevent 4E-BP1 phosphorylation, thereby suppressing the oncogenic translation program (DrugBank DB00877). Additionally, small molecules like 4EGI-1 are being explored to directly disrupt the eIF4E/eIF4G interaction, mimicking the inhibitory effect of hypo-phosphorylated 4E-BP1 (PubMed: 17301242). Because of its central role in the pathway, the phosphorylation state of 4E-BP1 is widely utilized as a pharmacodynamic biomarker to assess the activity of mTOR inhibitors in clinical trials (PubMed: 24469106). Safety concerns associated with modulating this pathway include metabolic side effects such as hyperglycemia and hyperlipidemia, as well as immunosuppression (StatPearls: mTOR Inhibitors).

Other names

EIF4EBP1PHAS-IPhosphorylated heat- and acid-stable protein IeIF4E-binding protein 1

mTOR inhibitors prevent the phosphorylation of 4E-BP1 by mTORC1, which maintains 4E-BP1 in its hypo-phosphorylated state, allowing it to bind and sequester eIF4E, thus inhibiting cap-dependent translation initiation.