FIG. 5.
Phosphorylation of Ctk1 is required for normal transcription of diauxic-shift genes. Total RNA was isolated from CTK1 (lanes 1 to 7) and ctk1T338A cells (lanes 8 to 14) during late exponential phase and early stationary phase (same time points as in Fig. 4A and B). Equal amounts of RNA were separated on a formaldehyde-agarose gel and probed for the presence of specific transcripts by Northern blot hybridization. TPK1, CTT1, and SPI1 transcripts were selected for analysis due to their differential expression in CTK1 and ctk1T338A cells in preliminary microarray hybridization experiments. ADH1 is a housekeeping gene and was used as a loading control. Its level is known to decline during stationary-phase growth. WT, wild type.