Association of human kinesin superfamily protein member 4 with BRCA2-associated factor 35.

A large portion of human kinesin superfamily protein member 4 (KIF4) is associated with the nuclear matrix during the interphase, while a small portion is found in the cytoplasm. During mitosis, it is associated with chromosomes throughout the entire process. In the present study, we identified a protein that interacts with KIF4 using a yeast two-hybrid system, co-immunoprecipitation and co-fractionation. This protein is BRCA2-associated factor 35 (BRAF35) containing a non-specific DNA binding high-mobility-group domain and a kinesin-like coiled-coil domain. It appeared that the interaction between the two proteins occurs through their respective alpha-helical coiled-coil domains. The co-fractionation experiment revealed that KIF4 and BRAF35 were present in a complex of approx. 540 kDa. The composition and biological significance of this complex should be studied further.