Mechanistic target of rapamycin

The mechanistic target of rapamycin, also known as mammalian target of rapamycin (MTOR) or FK506-binding protein 12-rapamycin-associated protein 1 (FRAP1), is a protein that in humans is encoded by the MTOR gene. MTOR is a serine/threonine protein kinase that regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, autophagy, and transcription. MTOR belongs to the phosphatidylinositol 3-kinase-related kinase protein family.

Discovery

MTOR was first named as the mammalian target of rapamycin. Rapamycin was discovered in a soil sample from Easter Island, known locally as Rapa Nui, in the 1970s. The bacterium Streptomyces hygroscopicus, isolated from that sample, produces an antifungal that researchers named rapamycin after the island.

Rapamycin arrests fungal activity at the G1 phase of the cell cycle. In mammals, it suppresses the immune system by blocking the G1 to S phase transition in T-lymphocytes. Thus, it is used as an immunosuppressant following organ transplantation.