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Fig. 3 | Journal of Animal Science and Biotechnology

Fig. 3

From: Novel metabolic and physiological functions of branched chain amino acids: a review

Fig. 3

Leucine increases protein synthesis by activation of the mTOR signaling pathway. Leucine enhanced muscle synthesis via the mammalian target of rapamycin (mTOR) pathway leading to phosphorylation of its downstream target proteins, eukaryotic initiation factor 4E-binding protein (4E-BP1) and p70 ribosomal S6 kinase 1 (S6K1). Under unphosphorylated conditions, 4EBP1 tightly binds to eIF4E, forming the inactive eIF4E · 4EBP1 complex. During anabolic conditions, mTORC1 induces the phosphorylation of 4EBP1, resulting in the dissociation of eIF4E from the inactive complex and allowing eIF4E to form an active complex with eIF4G. The process of association of eIF4E with eIF4G is obligatory for the binding of the 43S pre-initiation complex with mRNA. S6K1 is another mTORC1 substrate that participates in the regulation of mRNA translation. This kinase plays an important role in the regulation of terminal oligopyrimidine mRNA which is responsible for the translation of proteins involved in the protein synthetic apparatus

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