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.