Transcription regulator. Forms a sequence-specific DNA-binding protein complex with MAD1, MAD4, MNT, WBSCR14 and MLXIP which recognizes the core sequence 5'-CACGTG-3'. The TCFL4-MAD1, TCFL4-MAD4, TCFL4-WBSCR14 complexes are transcriptional repressors. Plays a role in transcriptional activation of glycolytic target genes. Involved in glucose-responsive gene regulation. Efficient DNA binding requires dimerization with another bHLH protein. Binds DNA as a heterodimer with MAD1, MAD4, MNT, WBSCR14 and MLXIP. Can also bind DNA as a homodimer. Found predominantly in the cytoplasm. Found predominantly in the cytoplasm. Found predominantly in the nucleus. Expressed in all tissues examined: stomach, duodenum, jejunum, ileum, colon, liver, pancreas, salivary gland, kidney, spleen, lung, heart, skeletal muscle, brain, ovary and testis. Expression peaks between dpc 9.5 to 11.5, then decreases during later stages of organogenesis.