We are interested in understanding the molecular networks that coordinate nutrient metabolism and cell growth. How cells assess nutrient- or energy states and relay this information into appropriate decisions on growth is poorly understood. Coordinate regulation of nutrient metabolism and cell growth is of fundamental importance, and many human diseases, such as cancer, diabetes, and developmental disorders, are affected by alterations in this process.Our research is focused on the mTOR signaling network that plays a crucial role in controlling cell growth in response to nutrient levels and growth factors. mTOR binds serveral proteins to form two distinct protein complexes. mTORC1 (mTOR complex 1) contains raptor (KOG1 ortholog), Gbl/mLst8, PRAS40 and DEPTOR, whereas mTORC2 (mTOR complex 2) conatins rapamycin insensitive companion of mTOR (rictor) (Avo3 ortholog), GbL/mLst8, Sin1 (Avo1 ortholog), PRR5/protor and DEPTOR. In spite of considerable efforts, it has not been possible to obtain a clear understanding of the molecular mechanisms by which the mTOR network is regulates by nutrient- and growth factor-signals. Utilizing novel moelcular biology and biochemical tool as well as a variety of structural approaches, we identify novel compnents and connectivity in the network and determine biological functions and signaling specificity thereof. Our recent studies have led us to identify PRAS40 and PRR5 as key components of mTORC1 and mTORC2. We investigate the functions of these newly-identified components in the regulation of cell growth and metabolism with linkw to human dieases such as cancer and diebetes. We anticipate this study will advance our understanding of the molecular bases underlying the coordinate regulation between metabolism and growth during animal development and the pathogenesis of metabolic diseases such as cancer and diabetes.