Anti-mTOR (mammalian target of Rapamycin): Marker for translation initiation activation

mTOR (mammalian target of Rapamycin), also named FKBP12 rapamycin-associated protein (FRAP/RAFT/RAPT/SEP), is a serine/threonine protein kinase that is an evolutionary conserved member of the phosphoinositol kinase-related kinase (PIKK) family that also includes DNA-PK, ATM, ATR and several other proteins [1-5]. mTOR is involved in the regulation of cell growth through initiation of gene translation in response to nutrients such as amino acids (mainly leucine), growth factors, insulin and mitogens. mTOR initiates translation by activating the ribosomal p70S6k protein kinase (S6K1) and by inhibiting the eIF4E inhibitor 4E-BP1. mTOR is thought to be involved in numerous additional cellular functions including actin organization, membrane trafficking, secretion, protein degradation, protein kinase C signaling, ribosome biogenesis and tRNA synthesis [1].

Rapamycin (R 0395) complexes with the immunophilin FK-506 binding protein FKBP12 peptide prolyl cis/trans isomerase. Interaction of this FKBP12-rapamycin complex with mTOR inhibits its function. It has been suggested that mTOR may sense cellular ATP levels and suppress protein synthesis when ATP levels decrease [6]. mTOR is phosphorylated at serine 2448 via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and is autophosphorylated at serine 2481 [7,8].

Anti-mTOR (FRAP) (T 2949) is produced using a peptide corresponding to amino acids 2433-2450 of human mTOR. The corresponding sequence is identical in mouse and differs by one amino acid in rat. The antibody specifically recognizes human, mouse and rat mTOR (289 kDa) and is suitable for immunoblotting, immunoprecipitation and immunofluorescence.

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