mTOR至少与两种蛋白形成功能蛋白复合物:RPTOR (Raptor, Regulated Associated protein of mTOR)和MLST8。这个复合物被称为哺乳动物TOR复合物1 (mTORC1)。RPTOR作为脚手架蛋白，架起mTOR与其底物相互作用的桥梁，定义了mTORC1的底物特异性(Dunlop et al. 2008)。MLST8增强了mTOR与RPTOR的关联。该复合物可通过与RHEB(一种小的鸟苷三磷酸(GTP)结合蛋白，在体内和体外有效激活mTORC1蛋白激酶活性(Long et al. 2005, Sarbassov et al. 2005)结合而被激活(Sancak et al. 2007)。Rheb与mTORC1相互作用并激活mTORC1(见Laplante & Sabatini 2009, Wang & Proud 2011)，是所有信号激活mTORC1所必需的。除了直接与mTOR结合外，RHEB还可以结合RPTOR和MLST8 (Hara et al. 2002, Inoki et al. 2005)。RHEB- gtp充电并不促进RHEB:mTOR的相互作用，但gtp充电的RHEB是激活mTOR催化活性所必需的(Avruch et al. 2009)。对裂变酵母的研究强烈表明，RHEB必须结合mTOR以激活催化活性(Urano et al. 2005)，这在哺乳动物中也得到了证实(Sancak et al. 2007)，尽管这一观点受到质疑(Wang & Proud 2011)。目前还不清楚活性mTORC1是否仍然与Rheb结合，或者，一旦被激活，是否可以与Rheb分离。 mTORC1 activity has been reported at many cellular localizations but some of these reports may be identifying mTOR as part of mTORC2. mTORC1 is predominantly lysosomal, though under amino acid starvation conditions it exhibits a diffuse, cytoplasmic distribution. It may have different functions when active in the cytoplasm. mTORC1 associates with the general translation initiation complex eIF3 and phosphorylates the translation inhibitor 4E-BP upon stimulation by growth factors and nutrients, promoting translation initiation (Proud 2009, Sonenberg & Hinnebusch 2009). These events presumably take place in the cytoplasm (Betz & Hall 2013).