ALL-1 INTERACTS WITH UNR, A PROTEIN CONTAINING MULTIPLE COLD SHOCK DOMAINS

The ALL-1 gene is involved in human acute leukemia through chromosome translocations and fusion to partner genes, or through partial tandem duplications, ALL-1 is the human homologue of Drosophila trithorax whi ch transregulates the homeotic genes of the Antennapedia and bithorax complexes controlling body segment identity, ALL-1 encodes a very larg e protein of 3968 amino acids which presumably interacts with many pro teins, Here we applied yeast two hybrid screening to identify proteins interacting with the N-terminal segment of ALL-1, One protein obtaine d in this way was the product of the unr gene, This protein consists o f multiple repeats homologous to the cold shock domain (CSD), a motif common to some bacterial and eukaryotic nucleic acids-binding proteins , The minimal region on unr required for the interaction with ALL-1 in cluded two CSD and two intervening polypeptides. The interaction was c onfirmed by in vitro binding studies, and by coimmunoprecipitation fro m COS cells overexpressing the relevant segments of the two proteins, These results suggest that unr is involved in an interaction of ALL-1 with DNA or RNA.