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Leucine

Branched-chain essential amino acid that acts as a signal for muscle protein synthesis via activation of mTORC1 through Sestrin2 and Rag GTPase signaling.

Also: L, Leu

A leucine threshold (~2.5-3 g per meal, or ~0.4 g protein/kg per meal) is required to maximally stimulate muscle protein synthesis in young adults; older adults exhibit anabolic resistance requiring higher per-meal doses. Leucine catabolism feeds into ketogenesis and TCA cycle anaplerosis via HMG-CoA and acetyl-CoA. Maple syrup urine disease (MSUD) is a branched-chain α-ketoacid dehydrogenase defect causing leucine accumulation.

How one textbook covers it

  • Modern Nutrition in Health and Disease, 12th ed. — Ch 1: Proteins and Amino Acids

    A leucine threshold (~2.5-3 g per meal, or ~0.4 g protein/kg per meal) is required to maximally stimulate muscle protein synthesis in young adults; older adults exhibit anabolic resistance requiring higher per-meal doses. Leucine catabolism feeds into ketogenesis and TCA cycle anaplerosis via HMG-CoA and acetyl-CoA. Maple syrup urine disease (MSUD) is a branched-chain α-ketoacid dehydrogenase defect causing leucine accumulation.

Related terms

Essential amino acid, Protein, Sarcopenia, mTORC1