Trans-acting factor that binds to glucocorticoid modulatory elements (GME) present in the TAT (tyrosine aminotransferase) promoter and increases sensitivity to low concentrations of glucocorticoids. Also binds to the transferrin receptor promoter. Essential auxiliary factor for the replication of parvoviruses. This is the function of GMEB2 (glucocorticoid modulatory element binding protein 2, ENSG00000101216).