A structural gene for the alpha-subunit of RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) has been identified and mapped between spcA and trkA, near 64 min on the E. coli chromosome. It appears to be coordinately expressed and possibly cotranscribed with the genes for ribosomal proteins S11, S4, and L17.