Repressor of translation initiation that regulates eIF4E1 activity by preventing its assembly into the eIF4F complex (PubMed:11389445, PubMed:19804760, PubMed:25702871). Hypophosphorylated form competes with eIF4G1 and strongly binds to eIF4E1, leading to repress translation (PubMed:25702871). In contrast, hyperphosphorylated form dissociates from eIF4E1, allowing interaction between eIF4G1 and eIF4E1, leading to initiation of translation (PubMed:25702871). Acts as a regulator of various biological processes, such as innate immunity, cell growth or synaptic transmission (PubMed:10811906, PubMed:11389445, PubMed:27525480). Acts downstream of phosphoinositide-3-kinase (PI3K) to regulate cell growth (PubMed:11389445). Extends lifespan upon dietary restriction by regulating the mitochondrial translation (PubMed:19804760). Acts as a regulator of lifespan in response to cold by regulating the mitochondrial translation (PubMed:28827349). Acts as a negative regulator of presynaptic release of neurotransmitter in motor neurons: Thor expression is induced in response to insulin signaling, leading to prevent of translation of complexin (cpx), a protein known to regulate the exocytosis of synaptic vesicles (PubMed:27525480). Acts as a negative regulator of synaptic strength at the neuromuscular junction: Thor expression in response to acute fasting prevents translation, thereby suppressing retrograde synaptic enhancement (PubMed:27916456). Hypophosphorylated Thor/4E-BP competes with eIF4G1 to interact with eIF4E1; insulin stimulated Akt1 or Tor phosphorylation of Thor/4E-BP causes dissociation of the complex allowing eIF4G1 to bind and consequent initiation of translation. Widely expressed. Expressed during all developmental stages. Up-regulated in response to bacterial infection (PubMed:10811906). Expression is induced by foxo: in neurons, foxo-dependent expression is activated in response to insulin signaling, while in muscle foxo-dependent expression is activated in response to fasting (PubMed:27525480, PubMed:27916456). The YXXXXLphi motif mediates interaction with eIF4E1 (PubMed:11389445). Compared to other members of the family this YXXXXLphi is atypical and interaction with eIF4E1 is weaker (PubMed:11389445). Phosphorylation at Thr-37, Thr-46, Ser-65 and Thr-70, corresponding to the hyperphosphorylated form, impairs its ability to prevent the interaction between eIF4G1 and eIF4E1, without affecting its interaction with free eIF4E1 (PubMed:14645523, PubMed:25702871). Phosphorylated in rtesponse to insulin (PubMed:11389445). Phosphorylation at Thr-46 is regulated by Tor and constitutes the major phosphorylation event that regulates activity (PubMed:14645523). Impaired innate immune response. Belongs to the eIF4E-binding protein family.