MTORC1

mTOR
Identifiers
Symbol	MTOR
Alt. symbols	FRAP, FRAP2, FRAP1
Entrez	2475
HUGO	3942
OMIM	601231
RefSeq	NM_004958
UniProt	P42345
Other data
EC number	2.7.11.1
Locus	Chr. 1 p36

RPTOR
Identifiers
Symbol	RPTOR
Alt. symbols	KOG1, Mip1
Entrez	57521
HUGO	30287
OMIM	607130
RefSeq	NM_001163034.1
UniProt	Q8N122
Other data
Locus	Chr. 17 q25.3

mTORC1, also known as mammalian target of rapamycin complex 1 or mechanistic target of rapamycin complex 1, is a protein complex that functions as a nutrient/energy/redox sensor and controls protein synthesis.

mTOR Complex 1 (mTORC1) is composed of mTOR itself, regulatory-associated protein of mTOR (Raptor), mammalian lethal with SEC13 protein 8 (MLST8) and the recently identified PRAS40 and DEPTOR. This complex embodies the classic functions of mTOR, namely as a nutrient/energy/redox sensor and controller of protein synthesis. The activity of this complex is regulated by rapamycin, insulin, growth factors, phosphatidic acid, certain amino acids and their derivatives (e.g., L-leucine and β-hydroxy β-methylbutyric acid), mechanical stimuli, and oxidative stress.

The role of mTORC1 is to activate translation of proteins. In order for cells to grow and proliferate by manufacturing more proteins, the cells must ensure that they have the resources available for protein production. Thus, for protein production, and therefore mTORC1 activation, cells must have adequate energy resources, nutrient availability, oxygen abundance, and proper growth factors in order for mRNA translation to begin.

Almost all of the variables required for protein synthesis affect mTORC1 activation by interacting with the TSC1/TSC2 protein complex. TSC2 is a GTPase activating protein (GAP). Its GAP activity interacts with a G protein called Rheb by hydrolyzing the GTP of the active Rheb-GTP complex, converting it to the inactive Rheb-GDP complex. The active Rheb-GTP activates mTORC1 through unelucidated pathways. Thus, many of the pathways that influence mTORC1 activation do so through the activation or inactivation of the TSC1/TSC2 heterodimer. This control is usually performed through phosphorylation of the complex. This phosphorylation can cause the dimer to dissociate and lose its GAP activity, or the phosphorylation can cause the heterodimer to have increased GAP activity, depending on which amino acid residue becomes phosphorylated. Thus, the signals that influence mTORC1 activity do so through activation or inactivation of the TSC1/TSC2 complex, upstream of mTORC1.

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