Rat1p maintains RNA polymerase II CTD phosphorylation balance

Excess Fcp1p rescues growth deficiency of rat1-1 cells. (A) Tenfold dilution series of wt and rat1-1 strains transformed with pRS425 or pRS425-FCP1 plasmids as indicated and spotted onto AA-Leu plates. Strains were grown for 3 d at 30°C or 34°C. (B) Rpb1p CTD phosphorylation status in whole-cell extracts measured by Western blotting analysis. Strains from A were grown at 30°C in AA-Leu medium to an OD₆₀₀ of 0.6, followed by a subsequent incubation for 1 h at 34°C, before being harvested for protein extraction. Membranes were probed with H14, H5, 3E8, 3E10, 4E12, Rpb1p (Y-80), or Fcp1p antibodies as indicated.