Primer extension reactions were performed as described previously [40] using a 59 32 P-labeled 18-mer DNA oligonucleotide complementary to the 59 region of the SSA1 mRNA (positions +1 to +19). Total RNA was extracted form S. cerevisiae cells that were grown in the presence or absence of 500 mg/ml MPA for 3 h at 30uC. The primer extension reactions were analyzed by electrophoresis through a 8% polyacrylamide gel containing 7 M urea in TBE and visualized by autoradiography.