INTERACTION OF KU PROTEIN AND DNA-DEPENDENT PROTEIN-KINASE CATALYTIC SUBUNIT WITH NUCLEIC-ACIDS

The Ku protein-DNA-dependent protein kinase system is one of the major pathways by which cells of higher eukaryotes respond to double-strand DNA breaks. The components of the system are evolutionarily conserved and homologs are known from a number of organisms. The Ku protein com ponent binds directly to DNA ends and may help align them for ligation . Binding of Ku protein to DNA also nucleates formation of an active e nzyme complex containing the DNA-dependent protein kinase catalytic su bunit (DNA-PKcs). The interaction between Ku protein, DNA-PKcs and nuc leic acids has been extensively investigated. This review summarizes t he results of these biochemical investigations and relates them to rec ent molecular genetic studies that reveal highly characteristic repair and recombination defects in mutant cells lacking Ku protein or DNA-P Kcs.