RNA polymerase II of Drosophila. Relation of its 140,000 Mr subunit to the beta subunit of Escherichia coli RNA polymerase.

We have determined the nucleotide sequence of the gene coding for the 140,000 Mr subunit of the DNA-dependent RNA polymerase II from Drosophila melanogaster. This analysis revealed features that are typical for a household-function gene. The codon usage is relaxed and there is no apparent TATA box upstream from the transcription start site. A comparison of the deduced amino acid sequence with that of the Escherichia coli RNA polymerase beta subunit shows a total of nine regions of homology. These regions are also conserved in chloroplast DNA of tobacco. This supports the notion that the two large subunits of the eukaryotic RNA polymerases are the structural and functional equivalents of E. coli beta' and beta subunits.