function:Unessential component of the TORC1 complex and essential component of the TORC2 complex. TORC1 controls cell growth in response to environmental signals, and is inactivated by nutrient limitation and environmental stress. Within TORC1, LST8 interacts directly with FRAP1 and enhances its kinase activity. In nutrient-poor conditions, stabilizes the FRAP1-RAPTOR interaction and favors RAPTOR-mediated inhibition of FRAP1 activity. TORC2 controls polarity of the actin cytoskeleton via the RAC1 pathway. TORC2 mediates phosphorylation of Akt/PKB on 'Ser-473' and phosphorylation of PKCalpha on 'Ser-657'.,similarity:Belongs to the WD repeat LST8 family.,similarity:Contains 7 WD repeats.,subunit:Interacts with FRAP1, RAPTOR and RHEB. Part of the target of rapamycin complex 1 (TORC1) which contains LST8, FRAP1, RAPTOR and AKT1S1. TORC1 binds to and is inhibited by FKBP12-rapamycin. Part of the target of rapamycin complex 2 (TORC2) which contains FRAP1, LST8, PROTOR1, RICTOR and MAPKAP1. Contrary to TORC1, TORC2 does not bind to and is not sensitive to FKBP12-rapamycin.,tissue specificity:Broadly expressed, with highest levels in skeletal muscle, heart and kidney.,