A Drosophila melanogaster homologue of the human DEAD-box gene DDX1.

DEAD-box genes are found throughout evolution and encode RNA-binding proteins. Such proteins include eukaryotic initiation factor-4A, which is essential for protein translation, Vasa, which is essential for germ line development, and a number of nuclear and mitochondrial RNA splicing factors. Transcription of a human DEAD-box gene, DDX1, is elevated in two retinoblastoma cell lines as a result of amplification of the immediate chromosomal region surrounding it, suggesting an important role for this gene in control of cell growth and division. We have isolated a Drosophila melanogaster (Dm) homologue (Ddx1) of DDX1 which is strikingly similar to the human gene. The similarity (58.3% amino acid (aa) identity over 720 aa) extends beyond regions conserved in all DEAD-box proteins and covers the entire lengths of the proteins. The 2.7-kb Dm Ddx1 RNA is expressed throughout development, but its levels are elevated in early embryos. Ddx1 maps to polytene chromosome band 79D4 on the left arm of Dm chromosome 3.