Mutations in plasmids encoding translin were generated by using the QuikChange site-directed mutagenesis kit (Stratagene, La Jolla, CA). The sequence of the whole translin gene was determined in all mutants to ensure that mutations only occurred in the desired locations. Oligonucleotides were purchased from Sigma and from MWG-Biotech AG. The plasmid expressing translin was kindly sent to us by Dr M. Kasai from the Department of Immunology, National Institutes of Health, Tokyo, Japan. This construct was made by cloning the translin cDNA into the plasmid pQE-9 (Qiagen), such that the recombinant protein expressed from this plasmid in E.coli bacteria includes a His6 tag at the N terminus