MLLT1 (MLLT1 super elongation complex subunit), also known as ENL or YEATS1, is a nuclear protein and core component of the super elongation complex (SEC) that plays a critical role in transcriptional regulation. The gene is located on chromosome 19p13.3 and encodes a 559-amino acid protein containing an evolutionarily conserved YEATS domain, an ANC1 homology domain, and intrinsically disordered regions. As an epigenetic "reader," MLLT1 recognizes acetylated and crotonylated lysine residues on histone H3 via its YEATS domain, thereby facilitating transcription elongation by RNA polymerase II and recruitment of chromatin remodeling complexes . MLLT1 is ubiquitously expressed in human tissues and is essential for embryonic development, as demonstrated by the embryonic lethality of Mllt1 knockout mice prior to 8.5 days post-coitum.