mAb 9E10 was injected into the cytoplasm of oocytes 1 h before injection of either myc-tagged coilin or myc-tagged PK. (A) Three hours later, a Western blot with mAb 9E10 as probe shows that both tagged proteins had translocated to the GV (left panel). At 18 h, GVs were isolated, and protein G-Sepharose beads were used to immunoprecipitate mAb 9E10. The presence of coprecipitated myc-tagged coilin or PK was demonstrated by Western blotting with mAb 9E10 as probe (right panel). (B) At 3 h (left panel) and 18 h (right panel) after nuclear injection, GVs were isolated, and proteins were precipitated as in A. Myc-tagged coilin was immunoprecipitated, whereas myc-tagged PK was not. The interpretation is that myc-tagged PK injected into the GV does not shuttle to the cytoplasm to react with mAb 9E10, whereas coilin does. Cyt, cytoplasm; S, supernate; IP, immunoprecipitate.