Transcriptional analysis of class I heat shock operons. Primer extension analysis of: (A) groESL, (B) dnaK, and (C) lp_rRNA01 transcripts. Primer extension products were obtained by using oligonucleotides groESL2, hrc2, and sed2, respectively. Total RNA was extracted from: LM3 cells grown at 30°C (lane 1), or after a 15 min heat shock at 50°C (lane 2); LM3-2 cells grown at 30°C (lane 3), or after a 15 min heat shock at 50°C (lane 4). As a reference, sequencing reactions were performed with the same primers.