Regulatory-associated protein of mTOR (Raptor) (p150 target of rapamycin (TOR)-scaffold protein)
function:Participates in the FRAP1 pathway and associates in a near stoichiometric ratio with FRAP1 to form a nutrient-sensitive complex (NSC). Plays a pivotal role as a scaffold protein in the FRAP1-signaling pathway and this interaction is essential for the catalyzed phosphorylation of EIF4EBP1. Has a positive role in nutrient-stimulated signaling to the downstream effector RPS6KB1. Under nutrient-deprived conditions, serves as a negative regulator of FRAP1 kinase activity. Regulation of the interaction with FRAP1 is a critical mechanism by which cells coordinate the rate of cell growth and maintenance of cell size with different environmental conditions.,miscellaneous:Rapamycin destabilizes the interaction with FRAP1 regardless of nutrient availability, and its potency for dissociation is increased under nutrient-rich conditions. This action uncouples FRAP1 from its substrates, and inhibits FRAP1 signaling without altering its intrinsic catalytic activity.,similarity:Belongs to the WD repeat RAPTOR family.,similarity:Contains 7 WD repeats.,subunit:Binds directly 4EBP1 and RPS6KB1 independently of its association with FRAP1. Binds preferentially to poorly or non-phosphorylated form of EIF4EBP1, and this binding is critical to the ability of FRAP1 to catalyze phosphorylation. Complex with FRAP1 physically interacts under both leucine-rich and -poor conditions and therefore in at least two nutrient-determined states with different stability.,tissue specificity:Highly expressed in skeletal muscle, and in a lesser extent in brain, lung, small intestine, kidney and placenta.,
