Repressor of translation initiation that regulates EIF4E activity by preventing its assembly into the eIF4F complex: hypophosphorylated form competes with EIF4G1/EIF4G3 and strongly binds to EIF4E, leading to repress translation. In contrast, hyperphosphorylated form dissociates from EIF4E, allowing interaction between EIF4G1/EIF4G3 and EIF4E, leading to initiation of translation (By similarity). Mediates the regulation of protein translation by hormones, growth factors and other stimuli that signal through the MAP kinase and mTORC1 pathways (PubMed:7629182). Hypophosphorylated EIF4EBP1 competes with EIF4G1/EIF4G3 to interact with EIF4E; insulin stimulated MAP-kinase (MAPK1 and MAPK3) or mTORC1 phosphorylation of EIF4EBP1 causes dissociation of the complex allowing EIF4G1/EIF4G3 to bind and consequent initiation of translation (PubMed:7629182). Interacts (via TOS motif) with RPTOR; promoting phosphorylation by mTORC1 (PubMed:24139800). Highest expression in fat cells. The TOS motif mediates interaction with RPTOR, leading to promote phosphorylation by mTORC1 complex. Phosphorylated on serine and threonine residues in response to insulin, EGF and PDGF. Phosphorylation at Thr-36, Thr-45, Ser-64 and Thr-69, corresponding to the hyperphosphorylated form, is regulated by mTORC1 and abolishes binding to EIF4E. Ubiquitinated: when eIF4E levels are low, hypophosphorylated form is ubiquitinated by the BCR(KLHL25) complex, leading to its degradation and serving as a homeostatic mechanism to maintain translation and prevent eIF4E inhibition when eIF4E levels are low. Not ubiquitinated when hyperphosphorylated (at Thr-36, Thr-45, Ser-64 and Thr-69) or associated with eIF4E. Mice lacking both Eif4ebp1 and Eif4ebp2 display increased their sensitivity to diet-induced obesity (PubMed:17273556). Mice lacking both Eif4ebp1 and Eif4ebp2 show defects in myelopoiesis: mice display an increased number of immature granulocytic precursors, associated with a decreased number of mature granulocytic elements (PubMed:19175792). Belongs to the eIF4E-binding protein family.