Abstract
Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder characterized by microcephaly, immunodeficiency, growth retardation, and cancer predisposition. Cells from NBS patients exhibit radiosensitivity, S-phase checkpoint defect, and chromosome instability. The gene product mutated in NBS, NBS1, forms a complex with MRE11 and RAD50 that is involved in the repair of DNA double-strand breaks and DNA damage checkpoints. However, the biological function of NBS1 has not fully been elucidated.
In this study, we tried to find previously unreported proteins that interact with NBS1. To search for NBS1-interacting proteins, we generated 293E derivative cell lines stably expressing FLAG/HA-tagged NBS1 and adopted a tandem affinity purification scheme. Western blotting confirmed that RAD50 and MRE11 were co-precipitated with tagged NBS1. Silver staining of the gel revealed that additional proteins were also precipitated with tagged NBS1. The protein bands were excised from the gel and subject to mass spectrometric analysis. The result of this analysis will be reported.
