regulatory-associated protein of mTOR; Raptor; P150 target of rapamycin (TOR)-scaffold protein (RPTOR, KIAA1303)

Function

• role in the FRAP1 (mTOR) pathway & thus the rate of cell growth & maintenance of cell size with different environmental conditions
• complexes with mTOR, negatively regulating mTOR kinase activity via a nutrient-sensitive complex
• role as a scaffold protein in the FRAP1-signaling pathway; interaction is essential for phosphorylation of EIF4EBP1
• positive role in nutrient-stimulated signaling to the downstream effector RPS6KB1
• under nutrient-deprived conditions, serves as a negative regulator of FRAP1 kinase activity
• binds directly 4EBP1 & RPS6KB1 independently of its association with FRAP1
• binds preferentially to poorly or non-phosphorylated form of EIF4EBP1, & this binding is critical to the ability of FRAP1 to catalyze phosphorylation
• complex with FRAP1 physically interacts under both leucine-rich & -poor conditions & therefore in at least two nutrient-determined states with different stability

Structure

• belongs to the WD repeat RAPTOR family
• contains 7 WD repeats

Alternative splicing

named isoforms=2

Expression

• highly expressed in skeletal muscle
• expressed to lesser extent in brain, lung, small intestine, kidney & placenta

Notes

• rapamycin destabilizes the interaction with FRAP1 regardless of nutrient availability, & its potency for dissociation is increased under nutrient-rich conditions; this action uncouples FRAP1 from its substrates, & inhibits FRAP1 signaling without altering its intrinsic catalytic activity

More general terms

• phosphoprotein
• WD repeat protein family

Component of

• target of rapamycin 1 complex (TORC1 complex)

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=57521
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:57521
• OMIM: https://mirror.omim.org/entry/607130
• UniProt: http://www.uniprot.org/uniprot/Q8N122.html