S-adenosyl-L-methionine-binding protein that acts as an inhibitor of mTORC1 signaling via interaction with the GATOR1 and KICSTOR complexes. Acts as a sensor of S-adenosyl-L-methionine to signal methionine sufficiency to mTORC1: in presence of methionine, binds S-adenosyl-L-methionine, leading to disrupt interaction with the GATOR1 and KICSTOR complexes and promote mTORC1 signaling. Upon methionine starvation, S-adenosyl-L-methionine levels are reduced, thereby promoting the association with GATOR1 and KICSTOR, leading to inhibit mTORC1 signaling. Probably also acts as a S-adenosyl-L-methionine-dependent methyltransferase. Interacts with the GATOR1 complex; interaction is disrupted when BMT2/SAMTOR binds S-adenosyl-L-methionine. Interacts with the KICSTOR complex; interaction is disrupted when BMT2/SAMTOR binds S-adenosyl-L-methionine. Belongs to the BMT2 family.