We exposed liver lysate to a cell-permeable, non-cleavable chemical cross-linker to trap native mTORC1 complexes, and again observed a marked decrease of free Raptor with aging or obesity, without change in other mTORC1/2 component distribution (Fig. 1c,d and Supplementary Fig. 1a–c). Here, RPTOR is linked to obesity due to melanocortin 4 receptor deficiency.