TC-O 9311 is an agonist of the orphan G protein-coupled receptor GPR139 (EC50 = 39 nM in a calcium mobilization assay).[1] It is selective for GPR139 over a panel of 90 additional targets. TC-O 9311 (1 μM) inhibits cell death induced by 1-methyl-4-phenylpyridinium (MPP+), but not 6-hydroxydopamine, in primary dopaminergic midbrain neurons.[2]

Reference:
[1]. Shi, F., Shen, J.K., Chen, D., et al. Discovery and SAR of a series of agonists at orphan G protein-coupled receptor 139. ACS Med. Chem. Lett. 2(4), 303-306 (2011).
[2]. Bayer Andersen, K., Leander Johansen, J., Hentzer, M., et al. Protection of primary dopaminergic midbrain neurons by GPR139 agonists supports different mechanisms of MPP+ and rotenone toxicity. Front. Cell. Neurosci. 10:164, (2016).