mTOR — mechanistic target of rapamycin, originally named for the macrolide rapamycin that inhibits it — is a serine/threonine kinase that integrates growth-factor, nutrient, and energy signals to control protein synthesis, autophagy, and cell growth. mTOR sits downstream of Akt in the PI3K-Akt-mTOR cascade.
Definition
mTOR is a large serine/threonine kinase of the PI3K-related kinase family that exists in two functionally distinct complexes: mTOR complex 1 (mTORC1, rapamycin-sensitive) and mTOR complex 2 (mTORC2, less rapamycin-sensitive). mTORC1 integrates inputs from growth-factor signalling (via Akt-mediated inhibition of the TSC1/TSC2 complex), nutrient availability (via amino-acid-sensing GATOR and Ragulator complexes), and energy status (via AMPK) to control cap-dependent protein synthesis through phosphorylation of S6K1 and 4E-BP1, and to suppress autophagy through ULK1 phosphorylation.
mTORC2 sits upstream of Akt rather than downstream — its phosphorylation of Akt on Ser473 is one of the two activating modifications required for full Akt activity. The reciprocal positioning means PI3K-Akt-mTOR signalling forms an interconnected network rather than a strictly linear cascade, with feedback loops that shape the dynamic response to receptor engagement at the membrane.
How mTOR is studied in peptide research
mTORC1 activity is measured by Western blot for phospho-S6K1 (Thr389) and phospho-4E-BP1 (Thr37/46) as the canonical downstream readouts, with phospho-S6 (Ser235/236) as the secondary marker for mTORC1-driven translation initiation. Pharmacological inhibition with rapamycin (mTORC1-selective in short-term exposure) or the ATP-competitive kinase inhibitors (mTORC1 + mTORC2) is used to confirm pathway involvement. mTORC2 activity is followed by phospho-Akt (Ser473) status.
For BPC-157, mTOR involvement is implicated downstream of the VEGFR2 → PI3K → Akt cascade documented in vascular endothelial cells (PMID 27847966), with the broader nitric-oxide-system synthesis (PMID 23755725) integrating downstream mTOR-axis outcomes. The 2024 comprehensive review consolidates the integrated signalling map across gastric, vascular, and multi-organ models (PMID 38980576), and the pleiotropic-activity review covers the wider receptor-and-cascade landscape (PMID 38675421).
Related terms
- Akt signalling
- PI3K
- VEGFR2
- Rapamycin
- S6K1 / p70S6 kinase
- 4E-BP1
- Autophagy
Compounds where mTOR appears in the mechanism literature
- BPC-157 — mTOR sits downstream of the VEGFR2-PI3K-Akt cascade implicated in the compound’s tissue-repair and cytoprotective findings
- TB-500 — protein-synthesis and cell-growth pathways via integrin-linked kinase signalling intersect with mTOR-axis outputs
- MOTS-c — mitochondrial-derived peptide with metabolic signalling that interacts with AMPK upstream of mTORC1
References
- Hsieh MJ et al. Therapeutic potential of pro-angiogenic BPC157 is associated with VEGFR2 activation and up-regulation. J Mol Med (Berl) 2017;95(3):323-333. [PMID 27847966]
- Sikiric P et al. Stable gastric pentadecapeptide BPC 157-NO-system relation. Curr Pharm Des 2014;20(7):1126-1135. [PMID 23755725]
- Sikiric P et al. New studies with stable gastric pentadecapeptide protecting gastrointestinal tract. Inflammopharmacology 2024;32(5):3119-3161. [PMID 38980576]
- Sikiric P et al. The Stable Gastric Pentadecapeptide BPC 157 Pleiotropic Beneficial Activity and Its Possible Relations with Neurotransmitter Activity. Pharmaceuticals (Basel) 2024;17(4):461. [PMID 38675421]
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.