BOVINE ALU-LIKE SEQUENCES MEDIATE TRANSPOSITION OF A NEW SITE-SPECIFIC RETROELEMENT

We describe a new family of 3.1-kb repetitive sequences which is prese nt in the bovine genome. The 5' and 3' ends of the unit are flanked wi th sequences homologous to the 5' and 3' halves of the bovine Alu-like monomer (BM), respectively. Distribution of the 5' ends of the family members in the genome is not random. They are close to the truncated bovine Alu-like dimer (BD) which, in some cases, is followed by 40-bp repeated sequences containing block A of the RNA polymerase III promot er, The ORFs found within the unit code for peptides homologous to ami no-acid sequences characteristic for reverse transcriptases (RT). The family members may be considered as mutant mobile elements whose propa gation in the genomes was accomplished by means of a process including site-specific recognition with BD. Because of this, we call this fami ly the bovine dimer-driven family (BDDF).