Abstract
When complexed with the intracellular protein FKBP12, rapamycin is a potent immunosuppressant and an inhibitor of a mitogen-stimulated signalling pathway that leads to activation of p70 S6 kinase (p70S6k) and cyclin-dependent kinases (CDKs). A recently cloned FKBP12-rapamycin-associated protein (FRAP/RAFT) is the likely mediator of these effects. Using FRAP variants that do not bind FKBP12-rapamycin, we demonstrate here that FRAP is a rapamycin-sensitive regulator of p70S6k in vivo and that the kinase activity of FRAP is required for this regulation. In addition, we show that FRAP autophosphorylates in vitro. Consistent with an essential role for FRAP kinase activity in vivo, autophosphorylation of FRAP is inhibited by FKBP12-rapamycin. Deletion studies indicate that the kinase activity of FRAP alone is not sufficient for control of p70S6k and that an amino-terminal domain in FRAP is also required.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Binding Sites
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Carrier Proteins / antagonists & inhibitors
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Carrier Proteins / metabolism
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Cell Line
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DNA-Binding Proteins / metabolism
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Enzyme Activation
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Heat-Shock Proteins / metabolism
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Hemagglutinin Glycoproteins, Influenza Virus
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Hemagglutinins, Viral / genetics
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Immunophilins*
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Phosphorylation
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Polyenes / pharmacology
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Protein Kinase Inhibitors
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Protein Kinases / metabolism
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Protein Serine-Threonine Kinases / metabolism*
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Recombinant Fusion Proteins / metabolism
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Ribosomal Protein S6 Kinases
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Sirolimus
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Tacrolimus Binding Proteins
Substances
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Carrier Proteins
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DNA-Binding Proteins
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Heat-Shock Proteins
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Hemagglutinin Glycoproteins, Influenza Virus
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Hemagglutinins, Viral
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Polyenes
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Protein Kinase Inhibitors
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Recombinant Fusion Proteins
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Protein Kinases
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Protein Serine-Threonine Kinases
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Ribosomal Protein S6 Kinases
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Tacrolimus Binding Proteins
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Immunophilins
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Sirolimus