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.