Myeloid/Lymphoid Or Mixed Lineage Leukemia Translocated To 1 (MLLT1)

ENL involved in recurring 11q23 leukemogenic translocations codes for an unusually large protein that is a homolog of Drosophila 'trithorax' and is involved in homeotic gene regulation (MLL). In studies of a t(11;19) translocation, they identified a chimeric protein containing the amino-terminal 'AT-hook' motifs of the MLL gene on chromosome 11 fused to a previously undescribed protein from chromosome 19. It is a nuclear protein that is capable of activating transcription from synthetic reporter genes in both lymphoid and myeloid cells, as well as in yeast. Deletion mutagenesis demonstrated that the minimal portion of the gene required for activation of transcription was located to its C-terminal 90 amino acids. This region is highly conserved between ENL and the t(9;11) fusion partner AF9 (MLLT3) and is retained in all fusion proteins.