The function of MLLT1 (MLLT1 super elongation complex subunit, Ensembl gene identifier ENSG00000130382) is as follows. Chromatin reader component of the super elongation complex (SEC), a complex required to increase the catalytic rate of RNA polymerase II transcription by suppressing transient pausing by the polymerase at multiple sites along the DNA (PubMed:20159561, PubMed:20471948). Specifically recognizes and binds acetylated and crotonylated histones, with a preference for histones that are crotonylated (PubMed:27105114). Has a slightly higher affinity for binding histone H3 crotonylated at 'Lys-27' (H3K27cr) than 'Lys-20' (H3K9cr20) (PubMed:27105114). May play a role in leukemogenic gene transcription (PubMed:39794553). {ECO:0000269|PubMed:20159561, ECO:0000269|PubMed:20471948, ECO:0000269|PubMed:27105114, ECO:0000269|PubMed:39794553}. Acts as a key chromatin reader in acute myeloid leukemia by recognizing and binding to acetylated histones via its YEATS domain, thereby regulating oncogenic gene transcription. .