FIG. 6.

Genetic interaction between kin28S^T162A and tfb3-ts. (A) Strains containing TFB3 or one of two temperature-sensitive alleles of tfb3 and either KIN28 or kin28^T162A were plated and grown at 26.5 and 34°C. Cells containing kin28^T162A alone showed no growth defect even at 37°C (data not shown). (B) The strains described for panel A as well as a kin28^T162A strain were grown at either 23 or 37°C for 4 h. Extracts were prepared, and Kin28p immunoprecipitates were assayed for CTD kinase activity (top panel) or immunoblotted for Kin28p (bottom panel). The apparently greater Kin28p^T162A activity seen in this figure compared to Fig. 3 reflects the longer exposure used in this experiment; Kin28p^T162A activity is still reduced by 75 to 80% compared to that of wild-type (WT) Kin28p.