Molecular genetic characterization of XRCC4 function

XRCC4 is a generally expressed protein of 334 amino acids that is involvedin the repair of DNA double-strand breaks and in V(D)J recombination, butits function is unknown. In this study, we have used a mutational approachand the yeast two-hybrid method to perform an initial characterization ofthis protein. We show that the XRCC4 protein is located in the nucleus. Wealso demonstrate that several potential phosphorylation sites are notrequired for XRCC4 function in a transient V(D)J recombination assay. Inaddition, we show that XRCC4 forms a homodimer in vivo with thehomodimerization domain being located within amino acids 115-204. Finally,we define a core domain of XRCC4 that functions in V(D)J recombination andcomprises amino acids 18-204. Potential functions of XRCC4 are discussed.