uPSEM792 is a pharmacologically selective effector molecules (PSEM) agonist for PSAM 4 -GlyR, with an affinity of K i of 0.7 nM. uPSEM792 is a substrate for efflux transporters in brains of wild type and dual P-gp and BCRP knockout mice. uPSEM7952 is a possible lead for developing the PET radioligand for PSAM 4 -GlyR.