FIG. 4.

In vivo coimmunoprecipitation. Whole-cell lysates were prepared from transfected cells, and the proteins complexed with PrKX were precipitated with an antibody to the poly-His tag fused to the amino terminus of PrKX. cos cells were transfected with a His-tagged PrKX expression plasmid only (lane 5) or were cotransfected with either Rep78 or Rep68 (lanes 6 and 7). As a control, cos cells were also transfected with either His-tagged Rep78 or Rep68 or untagged Rep78 or Rep68 and also precipitated (lanes 3, 4, 1, and 2, respectively). The complexes were then separated on polyacrylamide gels and probed for Rep by Western blotting with a Rep-specific antibody. Rep78 but not Rep68 was precipitated only when transfected with His-tagged PrKX (lanes 6 and 7, respectively).