The genes encoding the 52 ribosomal proteins (r-proteins) of Escherichia coli are organized into approximately 19 operons scattered throughout the chromosome. One of these, the spc operon, contains the genes for ten ribosomal proteins: L14, L24, L5, S14, S8, L6, L18, S5, L30 and L15 (rplN, rplX, rplE, rpsH, rpsH, rplF, rplR, rpsE, rpmD, and rplO). We now report the entire 5.9 kb nucleotide sequence of the apc operon. DNA sequence analysis has confirmed the genetic organization and refined the amino acid sequence of the ten r-proteins in this operon. It has also revealed the presence of two open reading frames past the last known gene (L15) of the spc operon. One of these corresponds to a gene (prlA or secY) which recently has been shown by others to be involved in protein export. In addition, Si mapping experiments indicate that a significant proportion of transcription initiated from the spc operon continues not only into the two putative genes, but also without termination into the downstream a r-protein operon. © 1983 IRL Press Limited.