The first enzyme in the electron transport chain. Complex I (also known as NADH Coenzyme Q oxidoreductase) is found in the mitochondria of eukaryotes and the plasma membranes of some bacteria. It couples the oxidation of NADH and the reduction of ubiquinone to provide the electrical gradient necessary to produce ATP. Complex I and its partner enzyme, complex III, are the primary sites of reactive oxygen species production in mitochondria. Mutations in complex I are associated with many disease conditions, including Parkinson's disease and Alzheimer's disease.

A naturally occurring substance capable of stimulating cellular growth, proliferation, healing, and differentiation. Growth factors typically act as signaling molecules between cells. Examples include cytokines and hormones that bind to specific receptors on the surface of their target cells.

One of the most potent natural activators of the AKT signaling pathway. IGF-1 stimulates cell growth and proliferation, inhibits programmed cell death, mediates the effects of growth hormone, and may contribute to aging and enhancing the growth of cancer after it has been initiated. Similar in molecular structure to insulin, IGF-1 plays a role in growth during childhood and continues later in life to have anabolic, as well as neurotrophic effects. Protein intake increases IGF-1 levels in humans, independent of total caloric consumption.

An enzyme that participates in genetic pathways that sense amino acid concentrations and regulate cell growth, cell proliferation, cell motility, cell survival, protein synthesis, autophagy, and transcription. mTOR integrates other pathways including insulin, growth factors (such as IGF-1), and amino acids. It plays key roles in mammalian metabolism and physiology, with important roles in the function of tissues including liver, muscle, white and brown adipose tissue, and the brain. It is dysregulated in many human diseases, such as diabetes, obesity, depression, and certain cancers. mTOR has two subunits, mTORC1 and mTORC2. Also referred to as “mammalian” target of rapamycin.

Rapamycin, the drug for which this pathway is named (and the anti-aging properties of which are the subject of many studies), was discovered in the 1970s and is used as an immunosuppressant in organ donor recipients.

A compound initially developed as an antifungal agent. This use was abandoned, however, when it was discovered to have potent immunosuppressive and antiproliferative properties due to its ability to inhibit one of the complexes of mTOR (mTORC1). Rapamycin has since shown interesting lifespan extension properties in animals.