[{"from": "human", "value": "Describe this molecule. [C][C@@H1][C][C][C@H1][C][C@@H1][Branch2][Branch2][=N][/C][=Branch2][Branch2][Branch2][=C][/C][=C][/C][=C][/C@H1][Branch2][#Branch1][=C][C][C@H1][Branch2][#Branch1][Branch2][C][=Branch1][C][=O][C@@H1][Branch2][=Branch1][=C][C@@H1][Branch2][=Branch1][=Branch2][/C][=Branch2][=Branch1][Ring2][=C][/C@H1][Branch2][Branch1][=C][C][=Branch1][C][=O][C][C@H1][Branch2][Ring1][P][O][C][=Branch1][C][=O][C@@H1][C][C][C][C][N][Ring1][=Branch1][C][=Branch1][C][=O][C][=Branch1][C][=O][C@@][Ring2][Ring2][Branch2][Branch1][Branch1][O][Ring2][Ring2][=Branch1][O][C@H1][Branch1][C][C][C][C@@H1][C][C][C@H1][Branch1][=Branch2][C@@H1][Branch1][Ring2][C][Ring1][=Branch1][O][C][O][C][/C][O][O][C][C][C][/C][O][C]"}, {"from": "gpt", "value": "The molecule is a natural macrocyclic lactone produced by the bacterium Streptomyces hygroscopicus, with immunosuppressant properties. In cells, sirolimus binds to the immunophilin FK Binding Protein-12 (FKBP-12) to generate an immunosuppressive complex that binds to and inhibits the activation of the mammalian Target Of Rapamycin (mTOR), a key regulatory kinase. This results in inhibition of T lymphocyte activation and proliferation that occurs in response to antigenic and cytokine (IL-2, IL-4, and IL-15) stimulation and inhibition of antibody production. (NCI04)"}]