UBP 310 is an antagonist of ionotropic glutamate receptor 5 (GluR5 or GluK1; Kd = 130 nM). It less potently binds GluR2 (GluA2) and GluR6 (GluK2; Kds = 106 and 1,626 μM, respectively). UBP 310 is inactive at metabotropic GluR group I and NMDA receptors.