YM-202074 is a high affinity, selective metabotropic glutamate receptor type 1 (mGlu1) antagonist. YM-202074 binds an allosteric site of the rat mGlu1 receptor with a Ki of 4.8 nM. It inhibits mGlu1-mediated inositol phosphates production (IC50 = 8.6 nM in rat cerebellar granule cells).