Acts as a DNA-binding transcriptional regulator involved in modulating the expression of genes responsive to glucocorticoid signaling (PubMed:12702733). Specifically binds AT-rich DNA motifs known as glucocorticoid modulatory elements (GMEs), repressing or enhancing transcription depending on cellular context (PubMed:10894151). Forms heterodimeric complexes with GMEB2, which enhances its DNA-binding specificity and transcriptional activity. This complex plays a critical role in the repression of glucocorticoid receptor (GR/NR3C1) transcriptional activity, acting as a negative modulator of glucocorticoid signaling (PubMed:10894151). Regulates dopamine-enriched midbrain genes, including tyrosine hydroxylase/TH and the dopamine transporter SLC6A3, essential for dopamine signaling (By similarity). Also binds the transferrin receptor promoter. In the cytoplasm, inhibits caspase activation and neuronal apoptosis by stabilizing CFLARL and blocking pro-caspase 8 activation (PubMed:31046799, PubMed:32514408). {ECO:0000250|UniProtKB:Q9JL60, ECO:0000269|PubMed:10894151, ECO:0000269|PubMed:12702733, ECO:0000269|PubMed:31046799, ECO:0000269|PubMed:32514408}. This is the function of GMEB1 (glucocorticoid modulatory element binding protein 1, ENSG00000162419).