CHARACTERIZATION AND CLONING OF P11, A TRANSREPRESSOR OF DROSOPHILA-MELANOGASTER RETROTRANSPOSON-1731

The NssBF element has been characterized as a 26 nt sequence in the lo ng terminal repeat of Drosophila melanogaster retrotransposon 1731, Th is sequence has been shown to be implicated in transcriptional repress ion of the 1731 promoter. We here report the cloning of a cDNA encodin g a nuclear DNA binding protein named pll that binds specifically to t he NssBF element, P11 is a 98 amino acid polypeptide, It exhibits simi larities with the mouse p9 single-stranded DNA binding protein, raisin g the possibility of a very general family of protein factors. Co-tran sfection experiments in human U937 cells showed repression of the 1731 promoter by overexpression of p11.