MLLT3, also named as AF9, YEATS3, is a 568 amino acid protein, which is a component of the superelongation complex6 and co-operates with DOT1L, which di/trimethylates H3K79 to promote transcription. MLLT3 localizes to active transcription start sites (TSSs) through the YEATS domain, which recognizes active histone marks such as H3K9 acetylation and crotonylation. A truncated MLLT3 that lacks the YEATS domain forms a leukaemic fusion protein with the N terminus of MLL1, which misdirects MLLT3-interacting complexes to induce aberrant gene transcription. MLLT3 also regulates erythroid or megakaryocytic progenitors and was identified as a definitive HSC hub gene during mouse development. Researcher found that the expression of a gene called MLLT3 was closely correlated with blood stem cells'potential to self-renew and that the protein generated by the MLLT3 gene provides blood stem cells with the instructions necessary to maintain its ability to self-renew. It does this by working with other regulatory proteins to keep important parts of the blood stem cell's machinery operational as the cells divide.