Fig. 5.

Subunits of the CAK Complex Enhance SF1-Dependent Transcription

A, H295R cells were transfected with SFRE/Luc (1 μg) together with expression plasmids encoding cycH (25 ng), MAT1 (10 ng), or CDK7 (10 ng). B, H295R cells were transfected as described in panel A, but with CYP17/Luc instead of SFRE/Luc. C, COS-1 cells were transfected with the CYP17/Luc, and an expression plasmid encoding SF1 (50 ng) together with cycH (50 ng), MAT1 (10 ng), or CDK7 (25 ng) expression plasmids as indicated in the figure. D, COS-1 cells were transfected as described in panel C, but with SF1(S203A) instead of SF1(WT). For all experiments, the luciferase activities in extracts from cells without exogenous expression of cycH, MAT1, or CDK7 were set to 1. Luciferase activities were calculated relative to β-gal activity (from pCMV5/βgal; 100 ng). All transfections were performed in triplicate repeated at least three times, shown as means ± sds. *, P < 0.05, as determined by Student’s t test. Cont, Control; n.s., not significant [P = 0.12 in panel B; P = 0.91 (cycH), 0.83 (MAT1), and 0.97 (CDK7) in panel D].