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. Binds also to the transferrin receptor promoter (By similarity). Homodimer, and heterodimer of GMEB1 and GMEB2. Interacts with the glucocorticoid receptor (NR3C1). May interact with CREB-binding protein (CBP) (By similarity). May be also cytoplasmic.