pp39(mos) is associated with p34(cdc2) kinase in c-mos(xe)-transformed NIH 3T3 cells

We investigated the possible interactions between pp39(mos) and p34(cdc2) kinase in NIH 3T3 cells transformed by c-mos(xe). pp39(mos) is coprecipitated with p34(cdc2) when using either anti-PSTAIR antibody or p13(suc1)-Sepharose beads. Likewise, p34(cdc2) is coprecipitated with pp39(mos) when using anti- mos antibody. However, pp39(mos) was not present in histone H1 kinase-active p34(cdc2) complexes precipitated with anti-p34(cdc2) C-terminal peptide antibody even during metaphase of the cell cycle. The molar ratio of p34 to pp39(mos) in the p13(suc1) complex is ~2:1. Consistent with the tight association between pp39(mos) and tubulin, tubulin was also present in equivalent amounts with pp39(mos) and p34 in the p13(suc1) complex. This pp39(mos)-p34(cdc2)-tubulin complex may be important in transformation by the mos oncogene.