AMPK (AMP-activated protein kinase)

AMPK — AMP-activated protein kinase — is a heterotrimeric serine/threonine kinase that functions as the cellular energy sensor, activating catabolic pathways and suppressing anabolic pathways when intracellular AMP/ATP ratios rise. AMPK is the dominant signalling node engaged by MOTS-c in metabolic-homeostasis research.

Definition

AMPK is a heterotrimeric serine/threonine kinase complex comprising a catalytic α-subunit and two regulatory subunits (β and γ). The α-subunit carries the kinase domain; the γ-subunit contains the AMP-binding sites that confer the energy-sensing function. When intracellular AMP and ADP levels rise relative to ATP (the canonical signal of cellular energy stress), AMP binding to the γ-subunit produces a conformational change that simultaneously protects an activating phosphorylation on Thr172 of the α-subunit from dephosphorylation, promotes the activating phosphorylation by upstream kinases (notably LKB1 and CaMKKβ), and directly allosterically activates the kinase domain. The net result is rapid AMPK activation under energy-stress conditions.

Active AMPK phosphorylates dozens of downstream substrates with the integrated effect of switching cellular metabolism from anabolic (energy-consuming) to catabolic (energy-generating) modes. Key outputs include activation of glucose uptake via GLUT4 trafficking, stimulation of fatty-acid oxidation via inhibition of acetyl-CoA carboxylase, promotion of mitochondrial biogenesis via PGC-1α activation, and suppression of protein synthesis through inhibition of mTORC1.

How AMPK is studied in peptide research

AMPK activation is measured by Western blot for phospho-Thr172 on the α-subunit alongside total α-subunit. Downstream readouts include phospho-ACC (acetyl-CoA carboxylase, an AMPK substrate) and the mTORC1-axis readouts (phospho-S6K1, phospho-4E-BP1) since AMPK activation suppresses mTORC1 signalling. Pharmacological AMPK activation with AICAR or A769662 and inhibition with compound C are standard tool-compound approaches for confirming pathway involvement.

For MOTS-c specifically, AMPK is the dominant published downstream signalling node. The original Lee characterisation established the metabolic-homeostasis phenotype in mouse models (PMID 25738459) with subsequent work mapping the muscle and adipose-tissue effects (PMID 27216708) and the metabolic-stress-responsive nuclear translocation behaviour (PMID 29983246). The Yang work characterised synergistic interaction between MOTS-c and exercise intervention in regulating PGC-1α expression and insulin resistance via AMPK signalling (PMID 33722744). The Jiang neuropathic-pain work documented AMPK-pathway involvement in MOTS-c’s effects on spared nerve injury (PMID 37285113).

Related terms

• MOTS-c
• mTOR (suppressed by AMPK)
• NAD+ (linked to AMPK via sirtuin signalling)
• LKB1 (upstream AMPK activator)
• PGC-1α / mitochondrial biogenesis
• Acetyl-CoA carboxylase (ACC)
• AICAR (pharmacological AMPK activator)

Compounds where AMPK appears in the mechanism literature

• MOTS-c — AMPK activation is the dominant published signalling node mediating the compound’s metabolic-homeostasis effects
• NAD+ — the NAD+/sirtuin axis interacts with AMPK in coordinated metabolic regulation
• 5-Amino-1MQ — NNMT inhibition modulates NAD+ pool size with downstream effects on AMPK-coupled metabolic regulation

References

1. Lee C et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab 2015;21(3):443-454. [PMID 25738459]
2. Lee C et al. MOTS-c: A novel mitochondrial-derived peptide regulating muscle and fat metabolism. Free Radic Biol Med 2016;100:182-187. [PMID 27216708]
3. Kim KH et al. The Mitochondrial-Encoded Peptide MOTS-c Translocates to the Nucleus to Regulate Nuclear Gene Expression in Response to Metabolic Stress. Cell Metab 2018;28(3):516-524. [PMID 29983246]
4. Yang B et al. MOTS-c interacts synergistically with exercise intervention to regulate PGC-1α expression, attenuate insulin resistance and enhance glucose metabolism in mice via AMPK signaling pathway. Biochim Biophys Acta Mol Basis Dis 2021;1867(6):166126. [PMID 33722744]
5. Jiang J et al. Mitochondrial-Derived Peptide MOTS-c Ameliorates Spared Nerve Injury-Induced Neuropathic Pain in Mice by Inhibiting Microglia Activation and Neuronal Oxidative Damage in the Spinal Cord via the AMPK Pathway. ACS Chem Neurosci 2023;14(13):2362-2374. [PMID 37285113]

Glossary entries describe research-context use of peptide-research terminology. They do not constitute medical, veterinary, or clinical advice. Every compound in the Ronin catalog is sold strictly for laboratory and research use only.