The function of MLLT10 (MLLT10 histone lysine methyltransferase DOT1L cofactor, ENSG00000078403) is as follows. Probably involved in transcriptional regulation. In vitro or as fusion protein with KMT2A/MLL1 has transactivation activity. Binds to cruciform DNA. In cells, binding to unmodified histone H3 regulates DOT1L functions including histone H3 'Lys-79' dimethylation (H3K79me2) and gene activation (PubMed:26439302). {ECO:0000269|PubMed:17868029, ECO:0000269|PubMed:26439302}.