| The transcription of one group of genes including rpb 3 , rpb 4 , rpb 5 , rpb 6 , rpb 7 and rpb 10 is mainly initiated at a single site , while that of the other group of genes for rpb 1 , rpb 2 , rpb 8 , rpb 9 , rpb 11 and rpb 12 is initiated at multiple sites . ^^^ Competitive PCR analysis indicated that mRNAs for Rpb 1 , Rpb 3 , Rpb 7 and Rpb 9 were among the group which had a low abundance , while the levels of Rpb 6 and Rpb 10 mRNAs were about fivefold , and that of Rpb 2 mRNA was about 40 fold higher than the Rpb 3 mRNA level . ^^^ |