High impact information on TOR

• Replacement of the Arabidopsis FKBP12 with the human FKBP12 allowed rapamycin-dependent interaction with TOR [1].
• RAPTOR1 also interacts in vivo with Arabidopsis S6K1, a putative substrate for TOR [1].
• TARGET OF RAPAMYCIN (TOR) kinase controls many cellular functions in eukaryotic cells in response to stress and nutrient availability and was shown to be essential for embryonic development in Arabidopsis thaliana [1].
• TOR (target of rapamycin) protein kinases were identified in yeasts, mammals, and Drosophila as central controllers of cell growth in response to nutrient and growth factors [2].
• A T-DNA-mediated translational fusion of AtTOR with the GUS reporter gene allows us to show that AtTOR is expressed in primary meristem, embryo, and endosperm, but not in differentiated cells [2].

Biological context of TOR

• However, research on TOR signaling in plants has been hampered by the natural resistance of plants to rapamycin [3].
• This is followed by the current status of the genetic analysis of the TOR gene in this plant and the search for potential members of a TOR pathway in the Arabidopsis genome [4].
• CONCLUSION: AML1 interacts with AtRaptor1B, homologue of a protein that recruits substrates for phosphorylation by the major cell-growth regulator TOR [5].
• These two proteins are known to bind to the catalytic subunit of PP2A and to function in the target-of-rapamycin signaling pathway [6].

Associations of TOR with chemical compounds

• The RAPTOR/KOG1 proteins are binding partners of the target of rapamycin (TOR) kinase that is present in all eucaryotes and plays a central role in the stimulation of cell growth and metabolism in response to nutrients [7].

Physical interactions of TOR

• Furthermore, pull-down assays demonstrated that TOR binds FKBP12 in the presence of rapamycin [3].

Other interactions of TOR

• However, Arabidopsis seedlings do not respond to normal physiological levels of rapamycin, which appears to be due its inability to bind to the Arabidopsis homolog of FKBP12, a protein that is essential for the binding of rapamycin with TOR [1].
• Identification of AML1 as a putative downstream effector of TOR gives valuable insights into the plant-specific mode of action of this critical growth regulator [5].
• The macrolide rapamycin specifically binds the 12-kD FK506-binding protein (FKBP12), and this complex potently inhibits the target of rapamycin (TOR) kinase [3].

References