FKBP12-Rapamycin-associated Protein or Mammalian Target of Rapamycin (FRAP/mTOR) Localization in the Endoplasmic Reticulum and the Golgi Apparatus

• Published in: The Journal of biological chemistry 2004-01, Vol.279 (1), p.772-778
• Main Authors: Drenan, Ryan M., Liu, Xiangyu, Bertram, Paula G., Zheng, X.F.Steven
• Format: Article
• Language: English
• Subjects: Animals; Carrier Proteins; Endoplasmic Reticulum - physiology; Golgi Apparatus - physiology; HeLa Cells; Humans; Mammals; Phosphotransferases (Alcohol Group Acceptor) - analysis; Phosphotransferases (Alcohol Group Acceptor) - physiology; Protein Kinases - analysis; Protein Kinases - physiology; Recombinant Proteins - analysis; Recombinant Proteins - metabolism; Tacrolimus Binding Protein 1A - analysis; Tacrolimus Binding Protein 1A - physiology; TOR Serine-Threonine Kinases; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M305912200

FKBP12-rapamycin-associated protein (FRAP) or mammalian target of rapamycin (mTOR) and its effector proteins form a critical signaling pathway that regulates eukaryotic cell growth and proliferation. Although the protein components in this pathway have begun to be identified, little is known about their subcellular localization or the physiological significance of their localization. By immunofluorescence, we find that both endogenous and recombinant FRAP/mTOR proteins show localization predominantly in the endoplasmic reticulum (ER) and the Golgi apparatus. Consistent with this finding, FRAP/mTOR is cofractionated with calnexin, an ER marker protein. Biochemical characterization suggests that FRAP/mTOR is a peripheral ER/Golgi protein with tight membrane association. Finally, we have identified domains of FRAP/mTOR which may mediate its association with the ER and the Golgi apparatus.