FIG. 7.

Rapid CTD phosphate turnover in CSF-arrested and interphasic egg extracts. (A) ³²P-labeled (on the CTD repeats) RNAP IIO was added to CSF-arrested egg extract. Samples were analyzed after increasing incubation times by autoradiography and Western blotting. The positions of the subunits IIa and IIo are indicated. (B) ³²P-labeled RNAP IIO was added to an egg extract that was either unactivated (▪) or activated (□) by Ca²⁺ at 22°C for 60 min. The percentage of radioactivity associated with subunit IIo (arbitrary units) is plotted as a function of time.